TOWARDS AN INTEGRATIVE CONCEPT OF CIRCADIAN PROCESSES: A - - PDF document

Poster Presentation No 1 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

TOWARDS AN INTEGRATIVE CONCEPT OF CIRCADIAN PROCESSES: A MATHEMATICAL MODEL OF SLEEP-WAKE CYCLES BASED ON NEURONAL ACTIVITY AND SYNAPTIC PLASTICITY.

Postnova S, Braun HA Institute of Physiology, Philipps University, Marburg, German Background: Biological activity is undergoing circadian alterations which can be seen in many physiological parameters like blood pressure, cortisol secretion and body core temperature. The circadian alterations of all these functions are closely interlinked and all of them are somehow coupled to the most prominent and immediately evident circadian process, the sleep-wake cycle. Decoupling of the different rhythms is discussed as a source for chronic diseases, including disturbances of the cardiovascular system and hormone secretion or mood disorders. A better understanding of the interlinks between the different functions can be important for the prevention and treatment of such diseases. Methods: In search for the interlinks between circadian mechanisms our focus is laid on neuronal activity and synaptic transmission. All the circadian functions are under neuronal control of different synaptically connected nuclei of the. In a first step, we have developed a novel, neuron-based concept of sleep-wake cycles which we have realized in a mathematical model. Results: Our model connects the circadian pacemaker in the suprachiasmatic hypothalamic nuclei (SCN) to homeostatic mechanism which we assume to originate from alterations of the synaptic efficacy of hypocretin/orexin (hcrt/ox) neurons in the lateral hypothalamus (LH). These neurons are firing during wake and are silent during sleep. We propose that high frequent impulse activity of the hcrt/ox neurons during the wake state is sustained by reciprocal excitatory connections with local glutamate neurons. The transition to a silent state is going along with a weakening of the synaptic efficacy, which is recovering in the sleep (silent) state. With sufficiently strong input by the SCN or external stimuli (alarm clock) the circuit can be reactivated. This model can reflect major features of sleep-wake cycles. Summary: We present a novel mathematical model of sleep-wake cycles as a first step towards an integrative concept of circadian functions. It is based on neuronal activity and synaptic transmission and has the major advantage that it can be extended with physiologically plausible assumptions to consider related alterations of homeostatic functions, i.e. energy control, hormone release and thermoregulation, and to analyse their mutual interdependencies.

Poster Presentation No 2 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

COMPUTATIONAL AND SYSTEM-THEORETICAL EXAMINATION OF EXPERIMENTAL RECORDINGS FORM AFFERENT COLD FIBRES AND COLD NEURONS' SOMATA.

Braun HA1), Huber MT1,2), Wollweber B1,3), Voigt K1) 1) Institute of Physiology, Philipps University, Marburg, Germany 2) Psychiatry Hospitals, Stade, Germany 3) Max-Planck-Institute for Psychiatry, Munich, Germany. We have used a computational study of cold transduction to elucidate possible reasons for seemingly inconsistent experimental data which were obtained 1) with extracellular action potential recordings from afferent cold fibres (e.g. Braun et al., Pflügers Arch. 386:1–9, 1980) and 2) with intracellular recordings of membrane potentials and ion currents from cold neurons' somata in the trigeminal and dorsal root ganglia (DRG). The latter attracted particular attention in suggesting cold and menthol sensitive TRP ion channels as the physiological correlate of cold sensation (e.g. McKemy et al., Nature 416:52-58, 2002; Peier et al., Cell. 108:705-715, 2002). The data from the cold neurons somata, however, are significantly different from those of peripheral receptors. Among others, they generally do show spontaneous discharges which is a major characteristic of cold receptors (Hensel et al. J. Physiol. 204: 99-112, 1969). Moreover, much stronger temperature changes are needed for the somata then for real receptors to induce transient responses and these occur only in a restricted temperature range. We assumed that the discrepancies might be due to the much bigger size of the somata compared to the receptors which means 1) higher membrane capacitance and 2) lower density of the functionally relevant ion channels in relation to the leak conductance. As this assumption cannot be proven experimentally we have used a previously developed computer model of cold receptors (Braun et al., Nova Acta Leopoldina. 88: 293-318, 2003) and could demonstrate that this model, indeed, can be converted into a soma model with increased capacitance and leak conductance: the spontaneous discharge was eliminated while the transient response persisted. We even could bring the model of the cell body back to spontaneous discharge with reduction of the K+-currents according to experimentally observed effects

• f 4-aminopyridine (de la Pena et al., J Physiol. 567: 415-426, 2005). However, although the response

characteristics seem to be the same as those of the original model, a more thorough comparison over the full temperature range exhibit significant differences, especially with regard to the impulse pattern. From a system-theoretical point of view, the models operates at different dynamic states.

Poster Presentation No 3 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

PARALLEL PREOPTIC PATHWAYS FOR INHIBITION OF THERMOGENESIS

Yoshida K1), Li X2), Ayoub I1), Cano G3), Lazarus M4), Saper CB1) 1) Department of Neurology and Program in Neuroscience,Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA, USA 2) Department of Cell Biology, College of Life Sciences at Wuhan University, Wuhan, Hubei, China 3) Department of Neurology, University of Pittsburg, Pittsburg, PA, USA 4) Department

• f Molecular Behavioral Biology, Osaka Bioscience Institute, Suita, Osaka, Japan

Sympathetic premotor neurons in the medullary raphe pallidus nucleus (RPa) appear to be a critical relay in the thermogenic pathway that increases body temperature under many physiological conditions. However, the origins of inputs to the RPa that activate it during cold exposure have not been definitively

• identified. We first investigated the origins of inputs to the RPa that show activation of cFos expression

during cold exposure and showed that cold activated neurons projects to RPa are located only in the dorsomedial nucleus and dorsal hypothalamic area (DMH/DHA). We also showed that there are two separate preoptic cell groups, the median preoptic nucle (MnPO) and the dorsolateral preoptic area (DLPO), each of which send independent projections both to the RPa and to the DMH/DHA. We then showed that cell specific lesions of both the median or dorsolateral preoptic area release a thermogenic response with a 1.5 degree C elevation of body temperature and blockade of fever responses, whereas individual lesions of either cell group do not increase body temperature, and only lesions of the median preoptic nucleus prevent fever responses. These data identified two parallel descending preoptic pathways for regulating body temperature.

Poster Presentation No 4 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

LATERAL PARABRACHIAL NEURONS THAT MEDIATE THE THERMOSENSORY AFFERENT SIGNALING REQUIRED FOR HEAT DEFENSE

Kazuhiro Nakamura, Shaun F. Morrison Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA In the regulation of body temperature in homeothermic animals, thermal afferents from the skin provide an important signal driving the rapid autonomic responses of thermoregulatory effectors to changes in ambient

• temperature. The preoptic area (POA) receives and integrates thermal information from the skin and other

thermoreceptive sites and sends efferent signals that alter peripheral effector activities to maintain body

• temperature. We have previously shown that the external lateral subdivision of the lateral parabrachial nucleus

(LPBel) contains neurons in the cool afferent pathway from the skin to the POA. In the present study, we found that a neuronal population in the dorsal subdivision of the LPB (LPBd), different from that involved in the cool afferent pathway, mediates warm afferent signaling to the POA for eliciting heat-defensive responses to environmental warming. Exposure of rats to a warm environment (36˚C, 4 hrs) induced Fos expression in neurons in the LPBd that were retrogradely labeled with cholera toxin b-subunit injected into the POA, while cold exposure (4˚C, 4 hrs) induced Fos expression in neurons in the LPBel that were retrogradely labeled from the POA. To investigate the functional significance of the warm-activated LPBd neurons projecting to the POA, we examined the effect of modulations of neuronal activity in the LPBd on the activity of the sympathetic, cutaneous vasoconstrictor (CVC) component of the sural nerve innervating the hind paw, which contributes to the control of heat dissipation, in urethane-chloralose-anesthetized rats. The activity of the sural CVC component was thermosensitive, spontaneously active when core temperature was at about 37.5°C, and was consistently inhibited by repeated, brief skin warming episodes. Inactivation of LPBd neurons with muscimol

• r blockade of glutamate receptors in the LPBd with a mixture of AP5 and CNQX that was bilaterally

nanoinjected eliminated the skin warming-induced inhibition of the spontaneous sural CVC activity. Glutamatergic stimulation of LPBd neurons with an NMDA nanoinjection inhibited the spontaneous sural CVC activity and also evoked an increase in tail skin temperature, responses consistent with increased dissipation of body heat. These results indicate that the afferent pathways for cool and warm signals from the skin to the POA are mediated by different populations of neurons in the LPB and that neurons in the LPBd mediate the transmission of warm signals from the skin to the POA that are required to defend body temperature in hot

• environments. Supported by NIH grant NS40987 and by the Japan Society for the Promotion of Science.

Poster Presentation No 5 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

Spinal glutamatergic and serotonergic neurotransmission contribute to EMG activation during skin cooling-evoked shivering.

Shaun F. Morrison, Kazuhiro Nakamura: Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA Shivering thermogenesis contributes both to the increase in body temperature during fever and to the maintenance of body core temperature during cold challenge where it is initiated in response to falls in skin or core temperatures sensed by cutaneous cool thermal receptors or by thermally-responsive central neurons, including those in the preoptic area (POA), respectively. We investigated the potential role of spinal glutamatergic and serotonergic neurotransmission in the skin and core cooling-evoked increases in nuchal muscle EMG in isoflurane-anesthetized rats. Both the cold-evoked activation of nuchal EMG and that following injection of prostaglandin E2 into the POA were reversed by inhibition of neuronal activity in the rostral raphe pallidus (rRPa), a site of glutamatergic and serotonergic neurons with projections to the spinal

• cord. Activation of rRPa neurons with local injection of NMDA or bicuculline elicited an increase in EMG
• activity. Nuchal EMG activity was elicited by injection of NMDA into the spinal ventral horn and cold-evoked

EMG activity was eliminated by injection of a mixture of AP5 and CNQX (5 mM each) into the cervical ventral horn throughout segments containing the nuchal muscle motoneurons. The amplitude of cold-evoked increases in nuchal EMG was reduced by > 60% following intravenous administration of the 5-HT2A receptor antagonist, ketanserin (2 mg/kg). Intravenous administration of the 5-HT2A receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI, 100 g/kg), elicited a prolonged increase in nuchal EMG in intact rats and in rats with cervical spinal cord transections that eliminated the nuchal EMG response to bicuculline injection into rRPa. These data are consistent with significant roles for the excitation of rRPa neurons and for the resulting activation of spinal glutamatergic and 5-HT2A receptors in contributing to the cooling-evoked increase in EMG activity that produces shivering thermogenesis. Supported by NIH grant NS40987 and by the Japan Society for the Promotion of Science.

Poster Presentation No 6 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

COMPARISON OF THE VMH, DMH AND PH IN THERMOREGULATION OF FREELY MOVING RATS

Takayuki Ishiwata1), 2), Hiroshi Hasegawa3), Takehito Saito4), Shigeki Nomoto2), Yasutsugu Aihara5) 1) Department of Sport and Wellness, Rikkyo University, Saitama, Japan, 2) Department of Central Nervous System, Tokyo Metropolitan Institute Gerontology, Tokyo, Japan, 3) Graduate of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan, 4) Daikin Industries, Ltd., Shiga, Japan, 5) Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan Background- Many reports have shown that the ventromedial hypothalamus (VMH), and posterior hypothalamus (PH) are important nuclei in heat production system such as non-shivering or shivering

• thermogenesis. Furthermore, dorsomedial hypothalamus (DMH) is recently well reported to relate in

non-shivering thermogenesis than VMH. The purpose of this study was to confirm changes of body temperature (Tb) and thermoregulatory responses after inhibition of neural activities in the VMH, DMH or PH

• f freely moving rats. In addition, since little is known about the pattern of monoamines releases in these nuclei,

we also measured their releases during active thermoregulation by high performance liquid chromatography (HPLC). Procedure- Telemetry device and microdialysis probe were implanted surgically prior to the commencement of the experiments. We perfused tetrodotoxin (TTX) solution into the VMH, DMH or PH using a microdialysis technique at two different ambient temperatures (5 or 23°C). We continuously measured the Tb and heart rate (HR) as an index of heat production by telemetry technique. Tail temperature (Ttail) as an index

• f heat loss was also continuous measured on the dorsal surface of the skin about 10cm from the tail base using

alumel-chromel thermocouple wire. Results- Although perfusion of TTX into each nucleus had no effect on all parameters under normal environment, this procedure into the DMH, PH but not the VMH induced hypothermia under cold environment. HR decreased only after perfusion of TTX into the PH during cold

• exposure. 5-HT in the DMH and dopamine metabolite DOPAC in the DMH and PH increased during cold
• exposure. Our results indicate that the DMH and PH but not the VMH are especially involved in heat

production system under cold environment. Serotonergic system in the DMH and dopaminergic system in the DMH and PH may be involved in heat production system.

Poster Presentation No 7 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECTS OF CENTRAL INFUSION OF CNTF ON THE ENERGETICS OF OBESE

• MICE. BIOTELEMETRIC STUDIES.

Szelényi Z1, 2), Solymár M2) 1) Department of Applied Life Sciences, Faculty of Health Sciences, 2) Department of Pathophysiology and Gerontology, Faculty of Medicine, University of Pécs, Hungary Background - Ciliary neurotropic factor (CNTF), an inducer of neurogenesis in the hypothalamus, has been shown to cause a permanent fall of body mass in mice made obese by a fat-rich diet (DIO), while in genetic

• besity this effect is transitory. Procedure - In the present study energetics of DIO mice has been followed

during and after intracerebroventricular (icv) infusion of CNTF (720 ng/day) using ALZET minipump for 7

• days. The animals were previously implanted with MINIMITTER biotelemetry transmitter allowing monitoring
• f abdominal core temperature (Tc) and locomotor activity (Act). Results - DIO food induced a rise in body

mass by about 40 % over a period of two months and led to a prompt decrease of circadian Tc amplitudes by about 50 % and an increase of 24 hrs Tc averages together with a decrease of Act. Icv infusion of CNTF resulted in an expected reduction of body mass of DIO mice beyond the period of infusion. This response was accompanied by a slight rise in daily averages of Tc together with an increase in Act. Conclusions - The

• bserved permanent fall of body mass may have been caused by the increased locomotor activity, but possible

changes of food intake – not measured in the present study – could have also contributed to the moderation of

• besity of these mice. Further studies are in progress to see, if CNTF had any influence on the energetics of

mice fed with standard rodent chow. Supported by the Hungarian National Science Fund (OTKA-T62598) and by a European grant (GVOP-3.2.1-2004-0271/3.0).

Poster Presentation No 8 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

INCREASE IN BODY TEMPERATURE INDUCED BY CRF AND UCN: A COMPARATIVE STUDY

Figueiredo MJ1), Fabricio ASC1), Soares DM1), Machado RR1), Souza GEP1) 1) Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences-USP, Ribeirão Preto-SP, Brazil Background - Corticotrophin-releasing factor (CRF) and urocortin (UCN) belong to CRF peptides family and, central injection of CRF increase body temperature of rats. This study compared the ability of CRF and UCN in inducing thermoregulatory response. The effect of antipyretic drugs and CRF receptors antagonists (CRF1 and CRF2) on the rectal temperature (rT) changes induced by these peptides was also investigated. Procedure - Rectal temperature (rT) and tail skin temperature (tsT) were measured by telemetry in male Wistar rats (200 g), each 30 min, by 6 h, after icv injection of CRF or UCN (1 nmol each). Rats received indomethacin (2 mg/kg); celecoxib (5 mg/kg) 30 min before, dexamethasone (0.5 mg/kg/ml, 1 h before), astressin (CRF1/CRF2 antagonist, 7 nmol, 15 min before) or antalarmin (CRF1 anta- gonist, 20 mg/kg, 2 h before). Results - The increase in rT caused by CRF and UCN was insensible to indomethacin and celecoxib. Dexamethasone did not modify UCN but attenuated the increase in rectal temperature to CRF (0.85±0.14 to 0.48±0.10ºC, 5th h, P< 0.05). The increase in body temperature induced by CRF was accompanied by a reduction in tsT (-0.04±0.18 to

• 0.68±0.25ºC, 1th h, P<0.05). UCN promoted an elevation in tsT (-0.11±0.25 to 1.03±0.14ºC, 2th h, P<0.05).

Astressin blocked UCN-induced hyperthermia (from 0.6±0.1 to 0.06±0.1ºC, 4th h, P<0.05) and CRF-induced fever (from 0.8±0.1 to 0.27±0.1ºC, 4th h, P<0.05). Antalarmin did not modify the hyperthermia to UCN, but reduced the fever evoked by CRF (from 1.5±0.17 to 0.8±0.17ºC, 3 h, P<0.05). Conclusions - CRF-induced increase in rT is a characteristic fever since this increase was parallel to a heat conservation response (cutaneous vasoconstriction) mediated by CRF1 receptors. UCN induced hyperthermia because the increase in rT was accompanied by a heat loss response (cutaneous vasodilatation) mediated by CRF2 receptors. Prostaglandins seem not to be involved in these responses. We showed before that endothelins and IL-1 are involved in the fever induced by CRF (Fabricio et al., 2006, Am J Physiol 290, 164) justifying the efficacy of dexamethasone in reducing the CRF-induced fever. Financial Support: FAPESP, CAPES, CNPq.

Poster Presentation No 9 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

HYPERTHERMIC ACTIONS OF INSULIN

Sanchez-Alavez, M1), Gomez LF3), Osborn O1), Mitsukawa K1), Hadcock JR2), Kolb H3), Secrest J3), Tabarean I1), Conti B1) and Bartfai T1) 1) The Scripps Research Institute, Molecular and Integrative Neurosciences Department, La Jolla CA, USA, 2) Pfizer Research, Groton CT, USA 3) Siemens Medical Solution, Culver City CA, USA. Temperature and energy homeostasis interdependently influence each other. Both are regulated centrally primarily by the hypothalamus where changes in both nutrients and temperature are detected. In the present study the effects of insulin on core body temperature, motor activity as well as metabolism were investigated. Microinjections of insulin into the preoptic area but not into other hypothalamic regions or the periphery induced dose dependent increases of core body temperature (CBT) and changes in oxygen consumption. The respiratory exchange ratio (RER) profile demonstrated that insulin increased CBT by simulating fatty acid utilization in the brown adipose tissue. These hyperthermic effects of insulin were inhibited pharmacologically with PIK3 inhibitors. Finally, when tested on isolated primary hypothalamic neurons insulin was demonstrated to act warm sensitive neurons. These data demonstrate that insulin can influence temperature and energy homeostasis by acting directly on warm sensitive neurons and eliciting BAT activation.

Poster Presentation No 10 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

ROLE OF BRAIN NITRIC OXIDE IN THE MAINTENANCE OF BODY TEMPERATURE OF BROILER CHICKS

Bícego KC1), Coleone AC1), Torres KAA1), Carnio EC2); Gargaglioni LH1), Macari M1), Furlan RL1) 1) Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil. 2 )Nursing School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil Background- Nitric oxide (NO) is known to act on brain to stimulate heat loss responses in mammals. Regarding birds, the putative participation of NO in the maintenance of Tb in thermoneutrality or during heat stress and the site of its action (periphery or brain) is unknown. Thus, we investigated if NO participates in the maintenance of chicks’ Tb in those conditions. Procedure - We verified the effect of intramuscular (im; 25, 50, 100 mg/kg) or intracerebroventricular (icv; 22.5, 45, 90, 180µg/animal) injections of L-NAME on Tb of 5-day-old chicks at thermoneutral zone (TNZ; 31-32ºC) and under heat stress (37ºC for 5-6h). We also measured plasma and diencephalic nitrite/nitrate levels in non-injected chicks under both conditions. Results - At TNZ, 100 mg/kg (im) or 45, 90, 180µg (icv) of L-NAME decreased Tb. A significant correlation between Tb and diencephalic, but not plasma, nitrite/nitrate levels was observed. Heat stress-induced hyperthermia was inhibited by all doses of L-NAME (im and icv). Tb was correlated neither with plasma nor with diencephalic nitrite/nitrate levels during heat stress. Conclusions – The present results indicate the involvement of brain NO in the maintenance of Tb of chicks, an opposite action of that observed in mammals, and may modulate hyperthermia induced by heat exposure. Financial Support: FAPESP.

Poster Presentation No 11 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

CLOCK GENE PLAYS AN IMPORTANT ROLE IN CIRCADIAN CHANGES IN THERMOREGULATION DURING FASTING IN MICE

Ken Tokizawa1), Yuki Uchida1), Kei Nagashima1), 2) 1) Laboratory of Integrative Physiology, Faculty of Human Sciences, and 2) Cosolidated Research Institute for Advanced Science and Medical Care, Waseda University, Tokorozawa, Saitama, Japan Background Food deprivation decreases body core temperature (Tb) in mice, which shows time-dependency: greater in the inactive (light) phase and smaller in the active (dark) phase. The purpose of the present study was to clarify the mechanism involved in the change of Tb rhythm during fasting. Procedure Male ICR wild-type (WT) and Clock mutant (CM) mice, housed at 27°C in a 12:12-h light-dark cycle were exposed to the cold at 20°C after 48-h fasting, corresponding to either at ZT1-4 (early light phase) or ZT13-16 (early dark phase). Tb (telemetry), oxygen consumption (indirect calorimetry), UCP1 mRNA level in the brown adipose tissues (RT-PCR), and cFos-immunoreactive (ir) cells in the hypothalamus (immunohistochemistry) were assessed. Results Tb decreased in the cold in all the groups. In WT, the reduction was greater in the light phase than in the dark phase; however, the reduction was similar in both the phases in CM. Oxygen consumption and UCP1 mRNA increased in the cold in the dark phase in WT and both the phases in CM, whereas remained unchanged in the light phase in WT. After the cold exposure, counts of cFos-ir cells in the medial preoptic area and paraventricular nucleus increased in all the groups: greater in the dark phase in WT and both phases of CM than in the light phase in WT. In the suprachiasmatic nucleus, counts of cFos-ir cells increased after fasting and the cold exposure had additive effect of the cFos expression in the light phase of WT. Conclusions These results indicate that fasting attenuates thermoregulatory responses to the cold, depending on time of the day. Neuronal activities in the medial preoptic area and paraventricular nucleus may be linked with the time-dependent thermoregulatory response in WT. In addition, the time-dependency of the thermoregulation and neuronal response in the two hypothalamic areas would be abolished in CM.

Poster Presentation No 12 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECTS OF MATERNAL FOOD RESTRICTION ON THE THERMOREGULATION OF THE OFFSPRING

LADEIRA T1), COELHO CT1), GUIMARÃES PB1), GOTO EM2), SILVA Jr JA2), HIRATA AE1), IHARA SSM2), NUNES, MT3), SILVA, SMA1), LUZ J1) 1) Department of Physiology, 2) Departmet of Pathology, Universidade Federal de São Paulo, Brazil; 3) Department of Physiology and Biophysics, Universidade São Paulo, São Paulo, Brazil. Background: Food restriction imposed during pregnancy usually leads to many alterations in the development

• f the conceptus. Previous study from our laboratory has shown that maternal food restriction (MFR) delayed

thermoregulation of the newborns. Uncoupling protein 1 (UCP1) is the responsible for non-shivering thermogenesis in the neonate and belongs to a family of UCPs, including UCP2 and UCP3. The aim of this study was to evaluate the effects of MFR on the UCP1, UCP2 and UCP3 expression in brown adipose tissue (BAT) of the neonates and theirs body composition. Procedure: Female Wistar EPM-1 control rats received food ad libitum during pregnancy period (C) and food-restricted group (R) received 50% of the amount ingested by C group. Fifteen hours after delivery newborns were sacrificed by decapitation and their carcasses were used for body composition determination. BAT were collected and kept at -80°C or kept in formol

• solution. UCPs mRNA was determined by real time PCR and proteins expression by immunohistochemistry.

Results: Offspring from R dams showed reduction on body weight and fat content and increased on water

• percentage. MFR led to an increase for UCP1, UCP2 and UCP3 mRNA and protein expression. Conclusion:

These results suggest an increase in heat losses by the increase in the ratio body surface/volume and impairment of thermal insulation that could be partially compensate by increased UCP expression. Thus, MFR delayed thermoregulation probably due to an increase in heat losses and not by impairment on thermogenesis. Finantial Support: FAPESP and CAPES

Poster Presentation No 13 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

CAN NOCTURNAL HYPOTHERMIA TELL US ANYTHING ABOUT ENERGY BALANCE IN LARGE FREE RANGING ANIMALS?

Maloney SK1, Meyer LCR3, Blache D2, Fuller A3

1Biomedical and Chemical Science,and 2Animal Biology, The University of Western Australia, Perth, Australia, 3Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South

Africa In rodents, fasting results in a change in the normal circadian body temperature rhythm with an exaggerated nadir during the quiescent phase of the cycle. We have observed similar variation in the pattern of the 24-h body temperature cycle in free-ranging animals (kangaroos, antelope, sheep). We hypothesised that energy intake might mediate changes in the normal temperature rhythm in large mammals. We altered systematically the energy intake of eleven ovariectomised Merino ewes housed indoors at a constant 22 – 23°C ambient

• temperature. We measured carotid arterial blood temperature, to a resolution and accuracy of 0.04°C, every 5

minutes with implanted data loggers. Fasting for 24 hours resulted in a significant decrease in the normal nocturnal body temperature nadir (37.9 vs 38.2°C, P<0.001), with no change in the diurnal body temperature zenith (39.2°C, P = 0.2). Fasting for 48 hours resulted in a larger decrease in the cycle nadir on the second night (37.8 vs 37.9, P = 0.005) and also a decrease in the diurnal zenith (38.8 vs 39.1°C, P = 0.01). In sheep fed a ration containing 1.5 times the maintenance energy requirements, neither the nadir or zenith of the circadian body temperature rhythm changed. In sheep restricted to 0.7 times the maintenance energy requirements the nocturnal body temperature nadir decreased (38.0 v 38.1°C, P = 0.008) with no change in the diurnal zenith (39.1°C, P = 0.47). Short-term fluctuations in energy intake produce identifiable changes in the circadian rhythm of body temperature of sheep. Our results may prove useful in extracting ecological useful information from the body temperature records of free ranging animals.

Poster Presentation No 14 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

THERMOGENIC UCP1 CONTROLES APPETITE THROUGH MODULATION OF LEPTIN SENSITIVITY

Yuko Okamatsu-Ogura1), Akira Terao1), Kazuhiro Kimura1), Masayuki Saito2) 1) Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, Japan 2) Department

• f Nutrition, School of Nursing and Nutrition, Tenshi College, Sapporo, Hokkaido, Japan

Background- Uncoupling 1 (UCP1) is a key molecule for the cold- and diet-induced thermogenesis in brown adipose tissue. Leptin, a hormone secreted by adipocytes, plays an important role in the regulation of appetite and energy

• balance. In addition to reducing food intake through the action on the hypothalamus, leptin increases energy

expenditure by activation of UCP1 through sympathetic nerves. To investigate the possibility that UCP1 is involved also in the anorexigenic effect of leptin, we analyzed the anorexigenic effect of leptin in wild-type (WT) and UCP1-deficient (UCP1-KO) mice. Procedure and Results- Single injection of recombinant leptin (5mg/kg, i.p.) decreased food intake similarly in WT and UCP1-KO

• mice. Repeated leptin injection (1mg/kg, s.c., twice a day, 3days) also decreased food intake in both mice,

while the anorexigenic effect tended to be weaker in UCP1-KO mice than WT mice. Almost the same tendency was observed when hyperleptinemia was induced by adenovirus gene transfer in WT and UCP1-KO mice. These results suggest that leptin sensitivity is increased in UCP1-dependent manner. As chronic leptin treatment is known to induce ectopic UCP1 expression in white adipose tissue (WAT), we investigated the effect of UCP1 expression in WAT on the anorexigenic action of leptin. In WT mice, 3-days injection of CL316,243 (0.1mg/kg, s.c.), a highly selective ß3-agonist, induced UCP1 expression in WAT without notable effects on WAT weight itself, and enhanced anorexigenic effect of leptin and leptin-induced phosphorylation of STAT3 in the hypothalamus. We also confirmed that a direct injection of UCP1-expressing adenovirus into WAT of UCP1-KO mice increased the leptin sensitivity. All these results suggest a role of UCP1 ectopically expressed in WAT in the control of leptin sensitivity. Conclusions- Ectopic UCP1 in WAT increases leptin sensitivity, and together with its thermogenic activity, contributes to the control of energy balance.

Poster Presentation No 15 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

PREVALENCE OF BROWN ADIPOSE TISSUE IN ADULT MEN: COMPARISON BETWEEN LEAN AND OVERWEIGHT

van Marken Lichtenbelt WD1), Vanhommerig JW1), Smulders NM2), Drossaerts JMAFL1), Kemerink GJ2), Bouvy ND3), Schrauwen P1), Teule GJJ2) 1) Department of Human Biology, 2) Department of Nuclear Medicine, and 3) Department of General Surgery, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University Medical Center+, Maastricht, The Netherlands. Introduction: Individual variation in adaptive thermogenesis can potentially be attributed to brown adipose tissue (BAT). Until recently presence of BAT was thought to be relevant in small mammals and infants only, while physiologically negligible in adult humans. The current study was undertaken to examine systematically presence and activity of BAT and its relation to body composition and energy expenditure. Methods: Adult lean (body mass index, 23.2 ± 1.2 kg/m2) and overweight (body mass index, 30.3 ± 4.2 kg/m2) men were studied during thermoneutrality (22 °C) and mild cold (16 °C). Bat activity during cold exposure was determined by FDG PET/CT scan. Body composition and energy expenditure were measured by DXA ad indirect calorimetry. Results: The prevalence of BAT was more than 95% in healthy adult men (23 out of the 24 subjects). BAT activity was significantly lowered in obese compared to lean subjects (p < 0.01), and negatively related to body mass index and to percent body fat, and positively related to resting metabolic rate. Conclusion: This study shows for the first time that BAT prevalence in adults is very high and that BAT activity is reduced in overweight men. It is negatively related to body mass index and percent body fat. BAT appears to be of metabolic significance in adult men. The fact that in most overweight subjects BAT is reduced but present, makes it an interesting target to treat obesity.

Poster Presentation No 16 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

THE BASIC REST-ACTIVITY CYCLE INCLUDES AN ULTRADIAN RHYTHM IN BROWN ADIPOSE TISSUE METABOLIC THERMOGENESIS

Ootsuka Y1), Menezes RC1), Stefanidis A2), Oldfield B2) and Blessing WW1) 1) Department of Human Physiology, Flinders University, Adelaide, SA, Australia, 2) Department of Physiology, Monash University, Clayton, VIC, Australia Purpose: Brown adipose tissue (BAT) temperature increases in an ultradian manner approximately every 90 min in rats, with these oscillations occurring throughout a wide range of environmental temperatures (18-28˚C)[1]. Since brain temperature has also been shown to have an ultradian rhythm, we assessed the contribution of BAT metabolism to these rhythms. We also determined whether bursts of BAT thermogenesis are integral components of the Basic Rest-Activity Cycle (BRAC), the fundamental 1-2 hour ultradian periodicity postulated by Kleitman [2], by correlating BAT metabolism with behavioral activity and with arousal-related (5-8Hz) theta rhythm in the hippocampal electroencephalograph (EEG). Methods: Rats (Sprague Dawley), anesthetized with Isoflurane, were instrumented with thermistors for continuous measurement of BAT, brain and body temperatures. In some rats EEG electrodes were also positioned in the dorsal hippocampus. Wires from probes were connected to a headpiece fixed to the skull. In another group of rats, telemetric temperature probes (TA-F40, DSI) were implanted to measure both BAT temperature and animal activity. At least one week later, conscious unrestrained rats were placed in a quiet constant temperature (24ºC) environment with 12-hour light/dark cycle. Results: During the 12 hour dark-active phase, BAT temperature increased by 1.1±0.1ºC every 82±3 min (n=129 phases in 9 rats), highly correlated with increases in brain temperature (R=0.92±0.05, n=14 in 9 rats), and in body temperature (R=0.71±0.8, n=14 in 9 rats), and in the proportional power of hippocampal theta-rhythm (R=0.59±0.03, n=45 in 7 rats). The hippocampal theta-rhythm became prominent 6±1 min (n=7 rats) before the onset of BAT thermogenesis. The increases in BAT temperature were ahead of brain temperature changes by 3±1 min (n=127 in 9 rats). Corresponding increases in behavioral activity were also observed with bursts of BAT metabolic thermogenesis, and were 7±1 min ahead of BAT temperature changes. Conclusion: We demonstrate that ultradian rhythmic change in brain and body temperatures partly result from heat production by BAT. Brain warming during the active phase of the 90-minute BRAC may be important for the brain to actively engage with the environment. We propose that this ultradian metabolic rhythm facilitates complex brain function in a manner that preserves energy stores. [1] Ootsuka et al, Soc for Neurosci. 2008, 83.2. [2] Kleitman N. Sleep 5: 311-317, 1982.

Poster Presentation No 17 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

ROLE OF SPINAL 5-HYROXYTRYPTAMINE (5-HT) IN COOLING-EVOKED SYMPATHETIC ACTIVATION OF BROWN ADIPOSE TISSUE

Madden CJ and Morrison SF Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA Neurons of the rostral raphe pallidus (RPa) play an essential role in the regulation of sympathetically-mediated metabolism and thermogenesis in brown adipose tissue (BAT). The presence of serotonergic neurons in the RPa that are retrogradely-labeled following pseudorabies virus injections into BAT suggests that these neurons play a role in the regulation of BAT. In urethane/chloralose-anesthetized rats, whole body cooling decreased skin (–5.7 ± 1.1 °C) and core (–1.1 ± 0.1°C) temperatures and resulted in an increase in BAT sympathetic nerve activity (SNA; +723 ± 172% of baseline activity, n=11). Microinjections of the broad spectrum 5-HT receptor antagonist, methysergide (10mM, seven to ten microinjections 100nl each, ~1mm apart rostrocaudally) into the T3 - T5 intermediolateral cell column (IML) attenuated the cooling-evoked (skin: –6.7 ± 2.4°C and core: –1.5± 0.2°C) increase in BAT SNA (area under the curve, AUC: 36 ± 9% of naïve cooling response, n=5). This methysergide-induced attenuation was characterized by a delayed increase in BAT SNA in response to cooling such that larger decreases in skin and core temperatures were required to increase BAT SNA. A similar microinjection paradigm using saline vehicle into the T3 – T5 IML did not affect the increase in BAT SNA (AUC: 100 ± 13% of naïve cooling response, n=6) in response to whole body cooling (skin: –5.4 ± 0.9°C and core: –0.8 ± 0.1°C). These results are consistent with our demonstration of a potentiating effect of 5-HT within the IML on BAT SNA and indicate that activation of 5-HT receptors in the spinal cord contributes to the cooling-evoked increase in BAT SNA. Supported by: DK065401 (CJM) and NS40987 (SFM).

Poster Presentation No 18 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

NON-INVASIVE MEASUREMENT OF SHIVERING IN BIRDS

Esa Hohtola, Ulla Koivukangas Department of Biology, University of Oulu, FIN-90014 Oulu, Finland The contractile activity of shivering muscles is usually measured by electromyography using intramuscular

• electrodes. This methods shows good correlation to overall heat production in the cold, but its use is limited to

situations were invasive techniques can be implemented. The gross tremors produced by shivering muscles could also be measured using accelerometers, but tremors depend heavily on the synchrony of contractions and thus do not indicate the number of active motor units very reliably. However, in addition to the electrical potentials produced by active muscle cells, the microvibrations (“myoacoustic” signals) that emanate from each contacting motor unit could, in principle, be used for measuring shivering quantitatively. To test this, we measured shivering activity in the pectoral muscles of Japanese quails (Coturnix japonica, N=8) and pigeons (Columba livia, N=8) by simultaneous electromyography and piezoelectric acoustic myography. The measurements were done at three ambient temperatures (10, -5, and -20 °C) both in control and cold-acclimated

• birds. For electromyograms (EMG), we used three intramuscular 3-mm needle electrodes fixed in an epoxy

plate in a triangular configuration. To measure acoustic myograms (AMG), we placed a piezoelectric sensor (R99-900, CliniLab, Finland, diameter 0.7 mm, length 7 mm) originally constructed for measuring eyelid movements in sleep studies adjacent to the EMG-electrodes. The sensors were taped securely to skin. The signals were amplified and filtered appropriately, and fed to an 16-bit A/D converter and sampled at 1000 Hz. Root mean square (r.m.s.) values of ca. 10-s data segments were used for estimating EMG- and AMG-amplitudes. AMG and EMG showed significant correlation in all individuals and at all tested ambient temperatures at two levels: 1) The correlations between the r.m.s. values of successive EMG- and AMG-segments were significant in each individual at each temperature. 2) The overall average r.m.s. values between temperatures always showed significant correlations in both species. Furthermore, the acclimation state of the bird had no effect on the relation between EMGs and AMGs. We conclude that acoustic myography is a convenient and inexpensive method to measure shivering.

Poster Presentation No 19 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECTS OF CHANGES IN AMBIENT TEMPERATURE ON RENAL AND LUMBAR SYMPATHETIC NERVE ACTIVITY IN CONSCIOUS RATS.

Kenju Miki, Misa Yoshimoto Integrative Physiology, Graduate School of Humanities and Sciences, Nara Women’s University, Nara, 630-8506, Japan. The present study examined interactions between changes in ambient temperature, renal (RSNA) and lumbar sympathetic nerve activity (LSNA), and physical activity levels in conscious rats. Male Wistar rats were chronically instrumented with electrodes for measurements of RSNA, LSNA, and electrocardiogram, electroencephalogram, electromyogram, with arterial and venous catheters, and with a thermocouple for measurement of intra-abdominal temperature. At least three days after the surgery, rats were exposed to 4 different ambient temperatures over 5 hours: 19, 24, 29, and 34 oC. The animal’s behavior was classified as non-REM (NREM) sleep, quiet awake, moving, and grooming states. During 19 oC exposure, both RSNA and LSNA were lowest during NREM sleep and rose linearly with an increase in physical activity in the order

• f quiet awake, moving, and grooming relative NREM sleep. This linear increase in RSNA and LSNA induced

by the increases in physical activity was persisted during the exposures of 24, 29, and 34 oC. Intra-abdominal temperature was remained unchanged throughout the exposures of 19, 24, and 29 oC. The increase in ambient temperature from 19 oC to 24 and 29 oC shifted the linear increase in RSNA and LSNA to downward in parallel manner in the order of 19, 24, and 29 oC. During 34 oC exposure, intra-abdominal temperature increased significantly (P<0.05) relative to that obtained during 19, 24, and 29 oC. The linear increase in RSNA induced by the increases in physical activity was shifted further downward during 34 oC exposure. However, during 34 oC exposure, the linear increase in LSNA induced by the increases in physical activity was shifted

• upward. Thus, 34 oC caused diverse changes in RSNA and LSNA. These data suggest that changes in

ambient temperature exert additive/substantive effect on the linear increase in RSNA and LSNA induced by changes in physical activity. The diverse changes in RSNA and LSNA may play a significant role in maintaining systemic arterial pressure by balancing vascular resistance among muscle, skin and vegetative

• rgans without interfering heat dissipation during 34 oC exposure.

Poster Presentation No 20 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

COOLING OF A NON-STIMULATED SKIN SITE INDUCED BY ACTIVATION OF SYMPATHETIC CUTANEOUS VASOCONSTRICTORS

Ho Hsin-Ni1), Craig AD2) 1) NTT Communication Science Laboratories, NTT Corporation, Atsugi, Kanagawa, Japan 2) Atkinson Pain Research Laboratory, Division of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona, USA Background- Vascular response to direct local cooling of the skin has been shown to involve sensory and autonomic systems, in which local cooling stimulates cold-sensitive afferents to activate cutaneous vasoconstrictors innervated the skin site. This study investigated whether the local cooling can also activates cutaneous vasoconstrictors innervated adjacent, non-stimulated skin sites. Procedure – The temperature responses of the non-stimulated middle finger were measured with a thermal camera prior to, during, and after the adjacent index and ring fingers touched the cold stimulators (each time period lasts for 10s). The initial skin temperatures were maintained above 30 oC using a hotplate and the cold stimulators are two copper blocks (20 x 40 x 140 mm) stored at room temperature. Results – Cooling the outer two fingers causes decrease in temperature on the non-stimulated middle finger, indicating the activation of sympathetic cutaneous vasoconstrictor at the middle finger. In general, the temperature of the middle finger started to decrease 2~3s after the outer two fingers touched the cold stimulators and the decrease was about 0.4 oC. In some cases, the temperature of the middle finger started to decrease before the cooling of the outer two fingers, suggesting the thought of touching the cold stimulators in a few seconds might also activate sympathetic cutaneous

• vasoconstrictors. After the outer two fingers withdrew from the cold stimulators, the temperature of the middle

finger gradually increased, indicating the vasoconstriction effects disappear after contact. Conclusions – Cooling of a non-stimulated skin site indicates that the sympathetic vasoconstrictors innervated the same skin site synergize with the regional sympathetic response to local cooling at the adjacent skin sites, leading to cutaneous vasoconstriction at the non-stimulated skin site.

Poster Presentation No 21 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

LOCAL ASCORBATE ADMINISTRATION INHIBITS ADRENERGIC VASOCONSTRICTOR RESPONSE TO DIRECT COOLING IN HUMAN SKIN

Fumio Yamazaki Laboratory for Human Physiology, School of Health Sciences, University of Occupational and Environmental Health, Kitakyushu, Japan Background - Local cooling of nonglabrous skin causes a vasoconstriction via adrenergic system and nitric

• xide (NO) system, but the detailed mechanisms of vasoconstriction are still unclear. In vitro study, cooling

increased reactive oxygen species in smooth muscle cells and induced an increased sensitivity of α-adrenergic

• receptors. It has been also reported that oxidative stress reduces NO bioavailability in human skin. Therefore

antioxidant supplementation may attenuate vasoconstrictor response to local cooling of skin via adrenergic and/or NO systems. To test this hypothesis, we examined the effects of acute L-ascorbate (Asc) supplementation in human skin on the vasoconstrictor responses to local cooling in skin with and without NO synthase (NOS) inhibition or adrenergic receptor blockade. Procedure - In a three-part study, forearm sites were instrumented with microdialysis fibers, local coolers, and laser Doppler flow (LDF) probes in healthy

• volunteers. Sites were cooled from 34 to 24˚C at -1˚C•min-1 and maintained at 24˚C for 10 min. Cutaneous

vascular conductance (CVC) was calculated as the ratio of LDF to blood pressure and expressed relative to the baseline value before cooling. Treatments in each part were as follows; 1) untreated (part 1); 2) Asc (part 1); 3) NG-nitro-L-arginine methyl ester (L-NAME) to inhibit NOS (part 2); 4) combined L-NAME + Asc (part 2); 5) propranolol (PRO) and yohimbine (YOH) to antagonize α- and β-adrenergic receptors (part 3); and 6) combined PRO + YOH + Asc (part 3). Results - In part 1, reduction of CVC during cooling was smaller (P<0.001) at Asc sites (-31±4%) than at untreated sites (-56±5%). In part 2, treatments of L-NAME tended to decrease the reduction of CVC at the two sites during cooling. Cooling-induced reduction of CVC was smaller (P<0.05) at L-NAME + Asc sites (-23±8%) than at L-NAME sites (-43±7%). In part 3, cooling-induced reduction of CVC did not differ between at PRO + YOH sites (-36±3%) and at PRO + YOH + Asc sites (-34±5%). Conclusions - These findings suggest that antioxidant supplementation inhibits vasoconstrictor response to direct cooling through adrenoceptor function in the human skin.

Poster Presentation No 22 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

VASCULAR RESPONSES IN GLABROUS AND NONGLABROUS SKIN DURING MENTAL STRESS IN PHYSICALLY TRAINED HUMANS

Fumio Yamazaki1), Hiroki Yano2), Ryoko Sone2) 1) Laboratory for Human Physiology, School of Health Sciences, University of Occupational and Environmental Health, Kitakyushu, Japan 2) Department of Exercise and Health Science, Faculty of Education, University of Yamaguchi, Yamaguchi, Japan Background – Mental stress influences vasomotor control in various organs including viscera, muscle and skin via the sympathetic nervous system, and the chronic exposure to mental stress induces neuropathy and peripheral vascular disorder. In the present study, to better understand the effect of physical training on peripheral vascular control during mental stress, we compared the skin vascular responses to acute mental stress in physically trained and untrained humans. Procedure – Eight trained (trained group) and eight untrained (untrained group) healthy volunteers were studied. Subjects performed 2 min of mental arithmetic aloud in the supine position under thermoneutral condition (28°C). Skin blood flow (laser-Doppler flowmetry) and local temperature were monitored at the nonglabrous (forearm, calf) and glabrous (palm, sole) sites. Cutaneous vascular conductance (CVC) was evaluated from the ratio of blood flow to mean arterial pressure (tonometry). Results – In the trained group, the CVC at glabrous sites consistently decreased (P<0.05) during mental arithmetic, while in the untrained group, the stress-induced decreases in CVC were transient and gradually recovered during mental arithmetic. The patterns of changes in CVC at nonglabrous sites were substantially similar with those at glabrous sites, but the decreases in CVC at nonglabrous sites were smaller (P<0.05) than those at glabrous sites in the two groups. Local temperature at glabrous sites (especially in sole) was higher (P<0.05) in the trained group than in the untrained group. Conclusions - These findings suggest that physical training does not change the central vasomotor control in the skin during acute mental stress during normothermia in healthy humans, but the vascular responses to mental stress may be modified by peripheral factors such as local temperature.

Poster Presentation No 23 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

AGE RELATED ATTENUATION OF CUTANEOUS VASOCONSTRICTOR RESPONSE DEPENDS ON MEASUREMENT SITE

Kingma BRM1), van Marken Lichtenbelt WD1), Frijns AJH2), Saris WHM1), van Steenhoven AA2) 1) Department of Human Biology, Maastricht University, Maastricht, The Netherlands 2) Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands Background: Cutaneous vasoconstriction (VC) induced by noradrenalin during local cooling is attenuated in aged ventral forearm skin. However, innervation and topology of cutaneous microcirculation is not

• homogenous. Which may imply that the magnitude of attenuated response over different skin sites could vary.

Therefore we tested the hypothesis that VC induced by noradrenalin during local cooling is blunted in aged skin of the dorsal and ventral side of the hand. Methods: Skin perfusion at ventral forearm, dorsal and ventral side of hand and mean arterial pressure (MAP) were measured in 16 juniors (18-28 years) and 16 seniors (68-78 years). Through iontophoresis of bretylium (10mM) local sympathetic nerve terminals were blocked. A baseline measurement was performed while clamping local skin temperature at 33C. Next, local skin temperature was clamped at 24C. After 10 minutes of cooling noradrenalin (2.5mM) was administered through

• iontophoresis. Results are expressed as cutaneous vascular conductance (CVC) percentage from baseline.

Results: A MANOVA was used to test for differences among age groups. Data are presented as mean %CVC±SE, F-statistic and p-value. VC induced by local cooling alone was similar in junior vs. senior

• subjects. Dorsal junior -32%±4% vs senior -28%±5% (F=0.69; p=0.41), ventral junior -34%±14% vs senior
• 30%±10% (F=0.79; p=0.38), forearm junior -21%±7% vs senior -14%±5% (F=0.77; p=0.39). After

noradrenalin VC at the hand is similar between groups, however, VC at the forearm differs. Dorsal junior

• 75%±4% vs senior -73%±4% (F=0.43; p=0.52), ventral junior -80%±7% vs senior -70%±9% (F=0.29; p=0.60),

forearm junior -76%±3% vs senior -60%±5% (F=8.78; p<0.01). Conclusion: Our results support previous findings that the vascular response to local cooling alone is maintained with age. Furthermore, we did find an age effect on the ventral forearm. However, our results show that there is no significant age effect on vasoconstrictor response of both glabrous and non-glabrous skin of the hand during local cooling.

Poster Presentation No 24 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

FREQUENCY ANALYSIS OF SKIN PERFUSION DURING WHOLE BODY COOLING IN GLABROUS AND NON-GLABROUS SKIN

Kingma BRM1), van Marken Lichtenbelt WD1), Frijns AJH2), Saris WHM1), van Steenhoven AA2) 1) Department of Human Biology, Maastricht University, Maastricht, The Netherlands 2) Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands Background: Skin vasomotion is composed of oscillating components, which are influenced by several mechanisms such as: cardiac activity (0.4 to 1.6Hz), respiration (0.15 to 0.4Hz), myogenic activity (0.06 to 0.15Hz), neural mechanisms (0.02 to 0.06 Hz), and endothelial mechanisms (0.0095 to 0.02Hz). During thermoregulatory challenges, e.g. whole body cooling, the centrally driven neural component may yield different local expressions in vasomotion due to differences in local innervations. Therefore we hypothesize that the neural frequency component during whole body cooling is equal in the ventral side in comparison to the dorsal side. To test this hypothesis we measured the neural frequency component of microcirculation during baseline (33°C) and whole body cooling (29°C) at the ventral and dorsal side of the hand. Procedure: 16 subjects (18 to 28 years) were tested. A water suit controlled skin temperature and laser Doppler flowmetry was used to measure skin perfusion. During a 15-minute baseline period skin temperature was controlled at 33°C and perfusion was measured. Next, subjects were cooled to an average skin temperature of 29°C for 30 minutes. Spectral power (contribution of the frequency component) was obtained by application of Fourier transform and normalized to the total power over the bandwidth. Pairwise testing was used for statistics. Results: Results are presented as mean difference and p-value. At baseline power at dorsal and ventral side do not differ significantly: dorsal-ventral = -0.006 m/s2 (p>0.85). However during whole body cooling power in the ventral hand is significantly higher: dorsal-ventral = -0.113 m/s2 (p<0.01). Conclusion: Results show that during whole body cooling the influence of the neural component to vasomotion at the ventral side of the hand is dominant as compared to the dorsal side. When studying the neural component in microcirculation spatial variation should be incorporated.

Poster Presentation No 25 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECT OF CALCIUM ON THE VASCULAR AND METABOLIC RESPONSE TO RAPID WARMING

Cheremisin A.S., Khramova G.M., Kozyreva T.V. Department of Thermophysiology, Institute of Physiology, Academy of Medical Sciences, Novosibirsk, Russia Background-It is known that calcium participates in forming of thermal afferent signal which determine the initiation and the order of various components of thermoregulatory response. In present work we studied the effect of iontophoretic application of calcium to the skin, where thermoreceptors are concentrated, on the temperature thresholds and values of metabolic and vascular response to warming. Procedure- The experiments were performed in rats. The experimental model was rapid warming (at a rate of skin temperature elevation 0.09˚C/sec when there are dynamic and static activities of skin thermoreceptors) up to the rectal temperature increase by 3˚C. The following parameters were recorded: total oxygen consumption, CO2 excretion, electrical activity of the neck muscle, rectal temperature, intracutaneous temperature in the abdominal area (to estimate the rate of skin warming), skin temperature of the auricle floor and tail (to estimate the vascular response in different regions). Calcium (10%) was applied 20 min at 0.08 mA/cm2 to the skin region, where the further thermal stimulus was applied. Results- Rapid warming caused the increase in heat loss and in the general metabolism. The sequence of initiation for various components of response to warming was as follows: firstly at increased skin temperature it was initiated vasodilatation in the ear skin, then at higher skin and additionally deep body temperature elevation the increase in metabolism and vasodilatation in the tail skin started. Although vasodilatation in the tail skin started later, its value was 2.5 times more compared to vascular response in the ear skin. The increase in oxygen consumption at warming was significant and reached 40-45 % without changes in muscle activity. Under the influence of calcium in thermoneutral conditions the respiratory coefficient decreased, that means that the fat metabolism portion enhanced. Calcium did not change the temperature thresholds for increase of metabolism and vasodilatation in the ear skin, but threshold of vascular response in the tail skin was decreased and its value increased significantly. Conclusion-The initiation

• f various components of organism response to warming in consecutive order may be due to activation of

different warm sensitive afferents. Possibility to change the temperature threshold of initiation one of the components of thermoregulatory response by calcium ions testifies to this point of view.

Poster Presentation No 26 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

MENTHOL SENSITIVE THERMORECEPTOR TRPM8 AND SENSATION TO COLD IN HUMAN

Elena Tkachenko, Tamara Kozyreva Department of Thermophysiology, Institute of Physiology, Academy of Medical Sciences, Novosibirsk, Russia Background-The relations between heat exchange and thermoregulation as a whole are reflected in thermal

• sensation. In recent years, numerous studies have been concerned with the molecular mechanisms of thermal
• sensitivity. It is believed that the thermosensitive TRP ion channels act as detector of changes in temperature.

The involvement of the menthol sensitive thermoreceptor TRPM8 in the formation of a conscience thermal sensation in human has been studied. Procedure-50 healthy volunteers were studied. Menthol (1%) was applied for 5 min on right forearm. The number of cold and warm spots (this was an estimate of the number of functioning cold and warm receptors) in an area of 25 cm2 of the forearm were determined. The effect of menthol on the cold receptor number was estimated 5 and 30 min after menthol application in the right forearm. Test cooling of the same intensity and duration was done before menthol application in the left forearm, and after it in the right forearm. Results- Menthol and test cooling had no effect on the number of warm spots in the forearm. There were variant groups due to individual sensitivity to menthol. Different responses to menthol were associated with different responses to cold. The main group 1 (70%) showed a decrease of cold spots (CS) 5 and 30 minutes after menthol application. They also showed the decrease in the number of CS to cooling before and after menthol application. In group 2 (14%) CS number increased 5 min after menthol application, and returned to the initial level after 30 min. Subjects of this group showed no significant change in CS number under test cooling before or after menthol application. Subjects of group 3 (16%) had no change in CS number after menthol application. Notably, the subjects of this group had no response to cooling before menthol application, but after it there is a distinct decrease in CS number in response to test cooling. Conclusion- Taken together, the results demonstrate that menthol, which along with cold activates the specific thermosensitive TRPM8 ion channels, may change the number of sensitive cold receptors, but is without effect on the warm receptor

• number. The disclosed group variants in menthol response may evidence for individual differences in TRPM8
• functioning. The results suggest that, based on the response variant to TRPM8 agonist the features of sensitivity

to cold may be predicted.

Poster Presentation No 27 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECT OF LONG-TERM AND SHORT-TERM COOLING ON EXPRESSION OF THE 1A AND 2A SEROTONIN RECEPTOR GENES IN THE HYPOTHALAMUS OF RATS.

Irina Voronova1), Alexandr Kulikov2), Valery Kozaruk1), Galina Chramova1), Tamara Kozyreva1) 1)Department of Thermophysiology, Institute of Physiology, Academy of Medical Sciences, Novosibirsk, Russia 2) Department of Behavioral Neurogenomics, Institute of Cytology and Genetics, Academy of Sciences, Novosibirsk, Russia Background - Investigation of neurogenomic mechanisms of temperature homeostasis of the homeotherms is an actual problem of the modern physiology. Alteration in proportion of monoamine receptors on the neuron’s surface may be one of the reasons causing the known changes in electro-physiologic characteristics of hypothalamic neuron in cold-adapted organisms. It was shown association of hypothermia or hyperthermia with activation of serotonin 1A or 2A receptors, respectively. Here the effect of cold exposure of different duration and intensity on the mRNA level of the 5HT1A and 5HT2A receptors in the rat’s hypothalamus was

• studied. Procedure - The level of mRNA was assayed by quantitative RT-PCR. The investigation was

performed on the rats after long-term cold adaptation (+4÷+6ºC for 5 weeks) and on the control ones (+20÷+22ºC for 5 weeks), as well as on the animals subjected to acute cold exposure – the cooling until rectal temperature fell by 3ºC. Results - It was found, that long-term cold adaptation increases the level of the 5HT2A receptor mRNA, but does not affect that of the 5HT1A receptor mRNA in the hypothalamus. These changes were hypothalamus specific and were not observed in other brain regions (frontal cortex, hippocampus, and midbrain). In the hypothalamus of rats subjected to acute cold exposure there was also found the alteration of ratio between mRNA of these two types of receptors: value of 5HT2A receptor mRNA per 100 copies 5HT1A receptor mRNA increased in comparison with control animals. Taking into account the specificity of these receptors effects on organism’s temperature balance it is possible to infer that the detected changes are adaptive. Conclusion - The data received confirm the assumption, that the processes of thermoregulatory reorganization may affect brain mediator’s receptors at the level of gene expression and alterations of this characteristic take place both after long-term cold adaptation and after acute short-term cooling.

• Acknowledgements. The work has been supported by Russian Foundation for Basic Research (grant

No06-04-49423-a).

Poster Presentation No 28 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECT OF ACTIVATION OF TRPM8 ON THERMOREGULATORY RESPONSE TO COLD EXPOSURE

Tamara Kozyreva, Valery Kozaruk, Galina Chramova Department of Thermophysiology, Institute of Physiology, Academy of Medical Sciences, Novosibirsk, Russia Background-It is assumed that thermosensitive TRP channels are detectors of temperature change and the main sensors in the peripheral nervous system. Several cold-transducing molecules have been identified. One

• f the most promising candidates is TRPM8, an ion channel activated by cold and menthol. TRPM8 is

preferentially expressed within a subset of rapidly responsive, low threshold cold-sensitive neurons. Participation of menthol-dependent thermoreceptors in formation of cold defense responses of an organism is not clear. In the present work we studied, if it is and how the activation of TRPM8 by its agonist menthol changes thermoregulatory responses of an organism to cold. Procedure- The effect of menthol on the temperature thresholds and values of the thermoregulatory responses to cooling was performed in rats. The experimental model was rapid cooling when there are dynamic and static activities of skin thermoreceptors (at a rate of 0.05˚C/sec) to a decrease in the rectal temperature by 3-4˚C. The following parameters were recorded: total oxygen consumption, CO2 excretion, electrical activity of the neck muscle, rectal temperature, intracutaneous temperature in the abdominal area (to estimate the rate of skin cooling), skin temperature of the auricle floor (to estimate the vascular response). Menthol (1%) was applicated to the skin, where thermoreceptors are concentrated and the following cold stimuli was applied. Rats without menthol application served as controls. Results-Activation of TRPM8 already in thermoneutral conditions caused increase of total

• xygen consumption and decrease of respiratory coefficient. The last may evidence that the fat metabolism

portion increased. The structure of thermoregulatory response to cold under the activation of TRPM8 also was changed: temperature thresholds of all thermoregulatory responses were decreased, values of the skin blood vessel constrictor response and shivering were without changes, while the value of nonshivering thermogenesis was two times increased. Conclusion- Menthol-dependent cold thermoreceptor TRPM8 even in thermoneutral conditions may participate in metabolism regulation. At rapid cooling activation of TRPM8 not changing the sequence of thermoregulatory responses facilitates its initiation and considerably intensifies the nonshivering component of cold thermogenesis.

Poster Presentation No 29 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

EFFECTS OF WIND AND RAIN ON THERMAL RESPONSES OF HUMAN IN MILDLY COLD ENVIRONMENT

Motoi Yamane1), Yukio Oida2), Norikazu Ohnishi3), Takaaki Matsumoto4), Kaoru Kitagawa4) 1) Department of Human Sciences, Aichi Mizuho College, Toyota, Aichi, Japan 2) School of Information Technology, Chukyo University, Toyota, Aichi, Japan 3) Faculty of Nursing, Mie Prefectural College of Nursing, Tsu, Mie, Japan 4) Laboratory for Exercise Physiology and Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota, Aichi, Japan Background - The physiology of accidental hypothermia is well documented from experimental studies of cold water immersion. However, research concerning the hypothermia occurring in the mountainous environment have been limited. The purpose of the present study was to clarify the effects of wind and rain on thermal responses of human in mildly cold environment. Procedure - Seven healthy young male subjects (mean ± SD: age 21 ± 1 yr, height 172.9 ± 5.0 cm, weight 66.0 ± 7.0 kg, body fat 12.5 ± 2.4 %) worn only shorts rested in a standing position for 20 min at an ambient temperature of 15 °C under three conditions: without exposure to wind or rain (CON), with exposure to wind (3 m/s) (WIND) and with exposure to wind (3 m/s) and rain (40 mm/h) (WIND+RAIN). Results - Mean heat loss measured by heat flux transducer was significantly greater at WIND+RAIN compared with CON and WIND (346.31 ± 34.21 vs. 156.79 ± 9.42 and 225.13 ± 18.14 W/m2; p < 0.01). Decrease in heat storage was significantly larger at WIND+RAIN compared with CON and WIND (-61.43 ± 10.72 vs. -29.17 ± 3.39 and -45.08 ± 6.47 kJ/m2; p < 0.01). However, no change in rectal temperature was observed in response to cold exposure at any conditions, and there was no difference among conditions. Mean skin temperature was significantly lower in WIND+RAIN condition than CON and WIND conditions (18.98 ± 0.88 vs. 26.19 ± 0.69 and 23.57 ± 0.66 °C; p < 0.01). Metabolic heat production was significantly greater in WIND+RAIN condition than CON and WIND conditions (101.38 ± 29.23 vs. 43.38 ± 4.01 and 45.37 ± 10.61 W/m2; p < 0.01). Conclusions - These results indicate that, although body heat loss significantly increases when the humans are exposed to wind and rain in mildly cold environment, core temperature is maintained by a shivering thermogenesis and shell insulation (peripheral vasoconstriction and subcutaneous fat).

Poster Presentation No 30 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

COMPARISON OF ENERGETICS OF SHORT-TERM COLD-ACCLIMATION IN NORMAL AND OBESE MICE: BIOTELEMETRIC STUDIES

Solymár M 1), Garami A 1), Pákai E 1), Szelényi Z 1, 2)

1)Department of Pathophysiology and Gerontology, Faculty of Medicine, 2)Department of Applied Life Sciences,

Faculty of Health Sciences, University of Pécs, Pécs, Hungary Background - Cold-acclimation in rodents is characterized by a rise of non-shivering thermogenesis and is supported by increased food intake. In mice energy balance may change more markedly because of the small body mass of that species, but changes in the dynamics of core temperature and locomotor activity during cold-acclimation under unrestrained conditions have not been studied so far in this species. Procedure - Minimitter biotelemetry transmitter (series 4000) was implanted into the abdominal cavity of C57BL6 mice under general anaesthesia. After stabilization in neutral temperature the animals were transferred to a cold room (4 oC) and held there for 1 to 2 weeks. Changes of core temperature and activity induced by cold exposure were analysed using Vitalview and Actiview software. In another group of mice made obese by a fat-rich diet cold-exposure was carried out under the same conditions. Results - In mice a robust fall of maximal (night) values of core temperature developed during the first three days of cold with similar fall of minimal (day)

• values. The 24-hour average of general activity showed a tendency to rise becoming significant from day 4
• nwards, a phenomenon most likely to be explained by a longer time needed for food intake related locomotor
• activity. In obese mice neither body core temperature, nor activity did change during cold exposure with a

minor decrease of body mass over the one week of exposure. Chronic methylprednisolone treatment in normal fed mice allowed a rapid adaptation to cold in terms of maintenance of circadian body temperature and activity

• rhythms. Conclusions - Changes of core temperature and activity should be studied also under conditions of

inhibition of shivering and/or non-shivering thermogenesis to learn about their possible role in the first stages

• f cold-acclimation in freely moving rodents having normal or high body mass.

Supported by the Hungarian National Science Fund (OTKA-T62598) and by an European grant (GVOP-3.2.1-2004-0271/3.0).

Poster Presentation No 31 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

ENHANCEMENT OF THE FINGER COLD-INDUCED VASODILATATION RESPONSE WITH EXERCISE TRAINING

Michalis E. Keramidas 1,2), Mojca Amon 2,3), Stylianos N. Kounalakis1), Igor B. Mekjavic1) 1) Department of Automatics, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia 2) Jozef Stefan International Postgraduate School, Ljubljana, Slovenia 3) Biomed d.o.o., Ljubljana, Slovenia Cold-induced vasodilatation (CIVD) is an acute increase in peripheral blood flow observed during cold

• exposures. This response has been suggested to provide protection against cold injuries. The purpose of this

study was to investigate the effect of continuous submaximal exercise training on the CIVD response. Ten healthy males (age=22.7±4.1 yrs, height=179.3±4.8 cm, mass=73.9±9.5 kg, body fat=10.8±3.0%) trained 1 h•d-1 on cycle ergometer at 50% of peak power output of pre-training VO2max, 5 d•wk-1 for 4-wks. The intensity

• f the daily exercise training was controlled via heart rate and rate of perceived exertion of each participant.

Pre- and post training subjects performed an incremental exercise test to exhaustion (VO2max), and a 30-min hand immersion in 8°C water to examine their CIVD response. VO2max increased significantly (P≤0.05) as a result of the exercise training (Pre: 44.9±6.5; Post: 51.2±6.0 mL•kg-1•min-1). Moreover, the continuous training protocol significantly increased the mean finger skin temperature (Tmean), the maximum temperature (Tmax) and the amplitude (Tmin-Tmax) of the hand CIVD response. Also, there was a tendency for increased frequency (number of waves; f) (P=0.07) and increased minimum temperature (Tmin) (P=0.06) post-training. In conclusion, the aforementioned continuous exercise training regimen potentially decreases the risk of cold injury in the hand by enhancing the CIVD response.

Poster Presentation No 32 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

PILOCARPINE-INDUCED SWEATING IN MALES AND FEMALES INDIVIDUALS.

Madeira LG¹, Fonseca MA¹, Fonseca IAT¹, Passos¹ RLF, Machado-Moreira CA² and Rodrigues LOC¹

1Exercise Physiology Laboratory, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 2School of

Health Sciences, University of Wollongong, Wollongong, NSW, Australia Background: Our understanding of central and peripheral mechanisms accounting for sex-related differences in the sudomotor function is incomplete. Unfortunately, the use of different stimuli (heat, exercise, drugs) to induce sweating, together with the typical differences in aerobic capacity (which may influence sweat secretion) observed between men and women, make the interpretation of the data available in the literature somewhat difficult. In this study, we investigated sex-related differences in the sudomotor responses to a cholinergic agonist, when males and females were grouped according to their aerobic capacity and when typical differences between sexes existed. Procedure: Forty four subjects were assigned to four groups: males with higher (MH) and lower (ML), and females with higher (FH) and lower (FL) aerobic capacity. During three experimental days, pilocarpine (0.125%, 0.250%, 0.5%, 1.0% and 2.0%) or pure water (control) was iontophoretically applied (1.5 mA, 60 A.cm-2, 5 min) at the anterior aspect of the forearms. In all trials, local sweat rate (absorbent paper) and the number of active sweat glands (iodine impregnated paper) were recorded. Results: For each group, gradual augments in sweating were observed as the drug’s concentration increased, until a plateau occurred, but significant inter-group differences were evident, with maximal pilocarpine-induced sweat secretion being greatest for MH, and lowest for FL (p<0.05). For within-sex comparisons, higher maximal pilocarpine-induced sweat responses were observed for MH and FH. However, no significant difference in the maximal sweating was observed between males and females when they were matched according to their aerobic capacity (p>0.05). Furthermore, across submaximal pilocarpine-induced sweat rates, men’s dose-response curves were shifted upwards, indicating that men displayed greater sudomotor responses (p<0.05), even when males and females had similar aerobic capacity. Finally, although the number of active sweat glands increased at higher doses of pilocarpine, no significant differences were observed among groups. Conclusion: We confirmed that sweating response is related to aerobic capacity, but we also observed that sex-related differences in sweat gland cholinergic sensitivity exist irrespective of differences in aerobic capacity. Nevertheless, whilst localized differences in the sudomotor function are likely to explain these findings, we did not observe significant variations in the sweat glands densities between men and women.

Poster Presentation No 33 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

DIFFERENTIATING THE THERMAL AND PSYCHOLOGICAL CONTROL OF HUMAN ECCRINE SWEATING

Machado-Moreira CA1, Barry RJ2, Ruest RM1, Taylor NAS1

1School of Health Sciences, University of Wollongong 2School of Psychology, University of Wollongong,

Wollongong, NSW, Australia Background: Non-glabrous and glabrous (hairless) skin surfaces are thought to possess different sudomotor responses, with the former responding to thermal stress, and the latter being affected mainly by psychological

• stimuli. Some have hypothesised the dual innervation of sweat glands, with a reciprocal inhibition between

thermal and psychological stimuli. Recent data from our laboratory are inconsistent with this hypothesis, indicating that when psychological stimuli are applied in the presence of thermal sweating, the non-thermal sudomotor responses of non-glabrous surfaces become more evident. In the current experiment, this hypothesis was further evaluated, but now in the absence of thermal sweating. Procedure: Sweating responses were evaluated (N=8) during mental arithmetic (10 min), using ventilated sweat capsules attached to four glabrous (palm, volar finger, sole, forehead) and five non-glabrous sites (chest, dorsal finger, hand, foot, forearm), and by measuring the skin conductance from the volar and dorsal aspects of the fingers. Prior to psychological stimulation, subjects rested (seated: 26oC) for 15 min. No thermal sweating was evident from any region. Heart rate, core and skin temperatures were also measured. Results: Significant increases in sweat rate during mental arithmetic were observed from all glabrous sites (P<0.05), except for the forehead (P>0.05), and from the non-glabrous surfaces of the fingers and foot (P<0.05). In addition, skin conductance was significantly augmented at both the glabrous and non-glabrous skin regions (P<0.05). These responses started immediately following, and were sustained throughout the stimulation. Similar responses were observed for heart rate (P<0.05), reflecting increased sympathetic drive. Nevertheless, no significant variation in mean body temperature occurred throughout these experiments (P>0.05), confirming the non-thermal origin of these

• responses. Conclusions: Psychological sweating was not restricted to the glabrous sites as some have

previously hypothesised. The current data, together with our previous observations, strongly refute the description of regional differences in either thermal or psychological sweating based exclusively on the division of skin into glabrous and non-glabrous surfaces. Moreover, these data fail to support either the existence of a dual innervation for eccrine sweat glands, or a reciprocal inhibitory mechanism between thermal and psychological sweating. We are currently attempting to identify the neuroendocrine mechanisms involved in thermal and psychological sweating.

Poster Presentation No 34 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

THERMAL AND NON-THERMAL SWEATING: WHAT YOU SEE IS NOT NECESSARILY WHAT YOU GET

Machado-Moreira CA1, Barry RJ2, Vosselman MJ1, Ruest RM1, Taylor NAS1

1School of Health Sciences, University of Wollongong 2School of Psychology, University of Wollongong,

Wollongong, NSW, Australia Background: Human eccrine sweating has been evaluated using many methods. However, when examining low-intensity sweating during psychological stress, or close to the thermal threshold, methods with greater temporal and spatial resolution are required. In this study, thermal and psychological sweating measured using ventilated sweat capsules were compared with data obtained by evaluating changes in skin conductance. Procedure: Fifteen subjects were engaged in two experiments. In experiment 1 (N=7), sweating was induced by passive heating (water-perfusion suit and foot immersion: 43oC). In experiment 2 (N=8), non-thermally induced sweating was elicited through a painful stimulus (standardised palmar pressure (15 s) using a pointed tool). Prior to each trial, subjects rested (seated: 26oC) for 15 min. Sweat rates (ventilated capsules) and skin conductance from the dorsal and volar surfaces of the fingers were continuously recorded. Results: Thermal sweating was evident only from the dorsal surfaces (P<0.05), and this was observed using both methods, although the onset of sweating was detected 4.4 min earlier from changes in skin conductance (P<0.05). That is, primary secretion into the secretory coil was evident from altered skin conductance, but this sweat did not immediately reach the skin surface, and was not detected by the sweat capsules. However, once thermal sweating was established, increments in mean body temperature elevated dorsal finger sweating, but these changes were only measurable from the sweat capsules. In experiment 2, pain-induced sweating was evident from both aspects of the fingers, using both techniques (P<0.05). However, the peak skin conductance occurred at least 20 s prior to the peak sweat rate (P<0.05). Despite these differences, data from both techniques were significantly correlated during the thermal and non-thermal stimuli in all experiments (P<0.05). Conclusions: The skin conductance technique has a much greater temporal sensitivity at low secretion rates, and this may have significant methodological implications for measuring thermal sweating thresholds. It is probable that, when primary sweat production is less than or equal to ductal water reabsorption, the sweat capsule method will fail to detect sweating. Thus, a failure to observe sweat secretion from sweat capsules may not always mean an absent sudomotor response, but may instead reflect a failure to detect sweating even though sympathetic drive has resulted in primary sweat production.

Poster Presentation No 35 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

REGIONALISED CUTANEOUS THERMOSENSITIVITY SUPPORTS THE CONCEPT OF TEMPERATURE RATHER THAN HEAT REGULATION

Cotter, JD1,2) and Taylor NAS2) 1) School of Physical Education, University of Otago, Dunedin, Otago, New Zealand, 2) School of Health Sciences, University of Wollongong, Wollongong, NSW, Australia. Background – Humans regulate an integrated composite of core and superficial body temperatures, though some maintain that body heat content is regulated. The 3-D arrangement of cutaneous thermoreceptors does provide the means through which heat flux may be transduced, and, during thermal transients there appears to be a closer relation between effector activity and changes in heat balance. We reexamined cutaneous thermosensitivities obtained using open-loop methods (Cotter & Taylor, J Physiol, 565: 335-345, 2005) to evaluate the possibility that high facial thermosensitivity could be more related to cutaneous heat flux rather temperature regulation. Procedure – Part 1: Regional thermosensitivities were quantified from changes in sweating (capsules on all limbs) upon warming and cooling (+4°C, -11°C) at each of ten locations (274 cm2) in resting males thermally clamped above the sweating threshold. Since conductive flux is linearly related to temperature difference, the derived thermosensitivities were normalised for regional differences in thermode-to-skin temperature gradients. Part 2: Five males undertook additional trials in which muscle, subcutaneous and skin temperatures were measured beneath thermodes on the thigh, chest and face. Results – Part 1: After normalisation for estimated heat flux, thermoeffector responses were again found to be larger for moderate cooling on the face than cooling on any other segment (P<0.01), and responses to warming on the torso and face were larger than for warming on the limb extremities (P<0.01). Part 2: Transcutaneous gradients in the face during local warming and cooling were smaller than those in the chest but larger than those in the

• thigh. Furthermore, sweat rate responses correlated as closely to skin (r=0.85) and subcutaneous (r=0.85)

temperature changes as they did to the transcutaneous gradients (r=-0.69; P=0.26). Conclusion – High facial thermosensitivities could not be explained by region-specific differences in indices of heat flux, and such

• bservations are inconsistent with heat regulation theory.

Poster Presentation No 36 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

REGIONAL DIFFERENCES IN THERMAL COMFORT

Nakamura M1), Kasuga M1), Yoda T4), Tokizawa K2), Uchida Y2), Crawshaw LI5), Nagashima K2, Kanosue K1 1) Faculty of Sport Sciences, 2) Faculty of Human Sciences, Waseda University, Tokorozawa, Saitama, Japan 4) Faculty of International Liberal Arts, Dokkyo University, Soka, Saitama, Japan 5) Department of Biology, Portland State University, Portland, OR, USA Background- Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into temperature sensation and thermal comfort. While several studies have investigated regional differences in temperature sensation, less is known about the sensitivity differences in thermal comfort for the various body

• regions. In the present study we examined regional differences in temperature-related sensations with special

attention to “thermal comfort”. In the previous study, we examined regional differences in thermal comfort among the face, chest, abdomen, and thigh. The comfort sensations seen in the study indicate that if given the chance, humans would preferentially cool the head in the heat, and maintain the warmth of the abdomen in the

• cold. In this study we analysed the thermal comfort of the hand, feet, and neck. Procedure - The neck, hand,

soles, and abdomen of healthy male subjects sitting in mild heat or cold were locally cooled or warmed. Local temperature sensation and thermal comfort of the stimulated areas were reported by the subjects, as was whole-body thermal comfort. Results - While no regional difference in “local” thermal comfort was observed between the hand and neck, the magnitude of decrease in “whole-body” thermal discomfort was smaller for the hand than for the neck both in the heat and cold. As for the neck, local cooling produced strong comfort during mild heat exposure, and produced no discomfort during mild cold exposure. This characteristic of the neck for local cooling is similar to that of the face obtained in the previous study. On the other hand, local warming of the neck produced strong comfort during mild cold exposure, and produced slight discomfort during mild heat exposure, and no difference was observed between the neck and abdomen for local warming. Conclusions – The hand was insensitive to produce whole body thermal comfort. The characteristic in thermal comfort of the neck was just in between those of the face and abdomen.

Poster Presentation No 37 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

BODY TEMPERATURE AND ACTIVITY CORRELATES OF THE MENSTRUAL CYCLE IN BABOONS, PAPIO HAMADRYAS

Nyakudya TT 1), Fuller A 1), Meyer LCR. 1), Maloney S 2), Mitchell D 1). 1) Brain Function Research Group, School of Physiology, University of the Witwatersrand, South Africa. 2) Physiology, University of Western Australia, Australia Background- Accurate determination of the phases of the menstrual cycle in primates is important for understanding their thermoregulatory function and reproductive success. We investigated the relationship between body temperature, activity, faecal and urinary hormones, and external reproductive changes over the menstrual cycle in baboons. Procedure- Miniature thermometric data loggers were surgically implanted intra-abdominally and activity loggers subcutaneously on the abdomen in five adult female baboons. Faecal and urinary samples were collected daily for hormone assays. Results- The length of the menstrual cycle, determined from daily observations of menstrual bleeding and anogenital swelling, was 37.6±4.5ºC days (mean±SD). Baboons exhibited a regular 24-h rhythm of body temperature and activity. Mean daily body temperature during the luteal phase (37.7±0.1ºC) was significantly higher than during the ovulatory phase (37.5±0.1ºC), but not different to the follicular phase (37.4±0.4 ºC). Activity followed a similar pattern, with mean 24-h activity almost twice as high in the luteal compared to the ovulatory phase. Conclusion- We have characterised correlates of the menstrual cycle in baboons and shown, for the first time in any species, a rhythm

• f both body temperature and activity over the menstrual cycle.

Poster Presentation No 38 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

OSCILLATIONS IN BRAIN TEMPERATURE AS A CONSEQUENCE OF NON-THERMAL INPUTS ALTER CORE TEMPERATURE OF NORMOTHERMIC SHEEP

Fuller A1, Hetem RS1, Meyer LCR1, Mitchell D1, Maloney SK1,2

1 Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South

Africa, 2 Physiology, School of Biomedical and Chemical Science, University of Western Australia, Perth, Australia Artiodactyls employ the carotid rete to lower brain temperature below arterial blood temperature, a process termed selective brain cooling (SBC). Unlike free-living artiodactyls, sheep in the laboratory have been reported to employ SBC at night when their body temperatures are low, and to exhibit frequent, transient

• scillations in brain temperature. We compared temperature patterns of eight female sheep (Dorper, 41±3kg)
• ver five days in an indoor animal facility (22-25°C) and five days at an outdoor agricultural facility (19-23°C),

by measuring brain (hypothalamic), carotid arterial and jugular venous blood temperatures at 5-min intervals using implanted miniature data loggers. We also determined the arteriovenous temperature difference (Ta-v) to estimate respiratory evaporative heat loss. The 24-h pattern of SBC was identical in both environments, despite greater fluctuations in carotid temperature in the field than indoors. On average, sheep employed SBC throughout the night, but SBC was abolished several times per night. SBC also was abolished at waking, and used sporadically during the day. Suppression of SBC arises from sympathetically-induced vasoconstriction, so is associated with events that invoke “flight of fright” responses. At night, increases in brain temperature probably reflect changes in sympathetic tone associated with a shift from slow-wave sleep to REM sleep. In each sheep over the five-day periods, changes in brain temperature were positively correlated to changes in Ta-v 5 min later, and negatively correlated to changes in carotid temperature 10 min later. These data support the idea that increases in hypothalamic temperature modulate thermoregulation by increasing evaporative heat

• loss. Small oscillations in brain temperature lead to inverse changes in carotid arterial (or core) temperature.

Oscillations in core temperature of sheep therefore may arise as a consequence of frequent brain temperature changes invoked by non-thermal inputs, both in animals housed in an indoor setting and in field conditions.

Poster Presentation No 39 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

RESPIRATORY COOLING AUGMENTS THERMAL SENSING IN THE RATTLESNAKE, CROTALUS DURISSUS

Tattersall, Glenn J.1) and Cadena, Viviana1)

1) Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada

Background - Snakes possess a profound degree of respiratory evaporation, which imparts significant cooling to the face and head. As pit vipers, rattlesnakes also utilize their forward-facing facial pit organs for sensing thermal fluctuations associated with their prey. The greater the difference in temperature between the prey and the pit organ, the greater the thermal flux; cooler pit organs, therefore, are hypothesized to provide greater thermal detection. Procedure - We examined the potential for respiratory cooling to enhance the rattlesnake’s ability to sense their endothermic prey by exposing two group of snakes to different humidities (45 and 95%) to manipulate the degree of respiratory cooling, while simultaneously assessing their capacity to track and find murine prey in complete darkness. Results - The latency for snakes to find and eat their prey was significantly longer at high than at low humidity, suggesting cooling increases thermal detection. These differences were accompanied by significant respiratory and facial cooling at low humidity compared to high

• humidity. Upon initial detection of mice, snakes exhibited a dramatic, slow (30s) respiratory cooling.

Conclusions – Inspiratory cooling of the upper airways cools the face and pits and can be augmented by the snake if necessary. This cooling imparts greater capacity to detect endothermic prey suggesting that snakes may exhibit some degree of respiratory control over thermal detection.

Poster Presentation No 40 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

CONTRACTILE PHYSIOLOGY OF ISOLATED TUNICA DARTOS MUSCLE IN RESPONSE TO ELECTRICAL THERMAL AND PHARMACOLOGICAL STIMULATION

Nanayakkara SDI, Bakker AJ, Maloney SK, School of Biomedical, Biomolecular and Chemical sciences, University of Western Australia, WA 6009, Australia Background - In most mammals testicular temperature is maintained 2-6°C below the core body temperature as spermatogenesis is a temperature sensitive process that is under the control of the hypothalamo-pituitary gonadal axis. The tunica dartos muscle lining the scrotal skin plays an important role in the regulation of testicular temperature and therefore, male fertility. Dartos contraction can be induced by sympathetic stimulation, and cold-induced contraction was previously thought to be mediated solely through a spinal reflex involving the sympathetic nerves and noradrenaline. However, cooling of the isolated dartos produces a contractile response indicating that other mechanisms also induce contraction in the dartos. Therefore, we have studied the contractile physiology of the isolated dartos muscle with regard to cold and pharmacological

• stimulation. Procedure - Isolated dartos muscle strips (2-3 mm wide) were obtained from the glabrous part of

the scrotum of Wistar rats and connected to a force transducer system in an organ bath. The bath contained Krebs-Ringer solution with a pH of 7.35. The bath was aerated with carbogen (5%CO2, 95%O2) and its temperature was controlled via a recirculating water bath. Results - The isolated dartos muscle contracted in response to electrical field stimulation (EFS) and exogenous noradrenaline (NA). The contractile response to cold stimulation was greater with the overlying skin present, compared to the isolated muscle (135±9.2% compared to 35.13±6.7% of EFS response, p<10-6, n=8). There was no significant difference in the response to EFS (p=0.51) and NA (p=0.15) when the skin was present or removed. The dose response curve to noradrenaline was sigmoidal with an EC50 of 10-5 M (n=6). Repeated cooling (after rewarming) led to a marked reduction in the contractile response to further cooling (3rd cooling peak tension 28.5±12% of 1st peak, n=6). No such reduction in response was observed with repeated EFS or NA stimulation. Prolonged cooling caused the tension to gradually decrease to baseline after an average of 72±4min, allowing the noradrenaline response at 15°C to be determined in the absence of cooling induced force. The contractile response to 10-5M noradrenaline at 15°C was 153% of that measured at 33°C. Removing extracellular calcium reduced the force response to NA to 68% of control, the EFS response to 83% of control, and cooling response to 75% of control. The dartos also responded with contraction followed by relaxation to exogenous ATP. The contractile response was 26.8% of the average EFS response and 23.9% of the average response to a submaximal dose of

• noradrenaline. Conclusions - This study shows that the cooling response in the tunica dartos is enhanced by

the presence of the skin, and the cooling response may be in part due to greater sensitivity to basal noradrenaline release at lower local temperatures. Calcium needed for contraction of the dartos comes mainly from the intracellular stores.

Poster Presentation No 41 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

RESPONSES OF PHYSIOLOGICAL PARAMETERS IN CATTLE TO INDUCED SHORT HEAT LOAD

Aharoni Y1), Brosh A2), Tahar E1), Abboud S3) 1) Veteix Ltd, Veterinary Expert systems, P.O.B. 36 Or Aqiva 30600, Israel 2) Beef Cattle section, Department of Cattle and genetics, Institute of Animal Sciences, ARO, Newe Yaar P.O.B 1021 Ramat Yishay 30095, Israel 3) Department of Medical Engineering, Tel Aviv University, P.O.B 39040 Tel Aviv 69978, Israel Introduction: Changes in the physiological status of an animal are reflected in change in levels of some of its physiological parameters such as temperature, heart rate, etc. Therefore, detection of events such as illness, parturition, estrus or stress conditions that affect the physiological status will be possible if these parameters are monitored continuously and interpreted in real time. Technology: The basic physiological parameters in cattle are now monitored continuously by a system that was developed by Veterix, Israel. The system comprised of capsules, which are inserted through the mouth to the reticulum (the first stomach) of cows and record at 5-min intervals the following physiological parameters: heart rate (HR, beats/min), respiratory rate (RR, breaths/min), interval between rumen contractions (RI, seconds) and rumen temperature (RT, 0C). These data are transmitted by RF communication to a central computer unit that stores the data, presents the curves with time of the physiological parameters for each cow upon request and interpret the data to produce a set of alerts to the herd

• manager. Observations: Ruminal T was found higher by about 0.60C than vaginal T. This higher level was

sharply dropped down for a short while following water drinking by the animal. The higher level of ruminal T, compared with vaginal T, can be explained by a gradient of T from more internal to less internal organs. However, this difference was higher in milking cows then in dry cows consuming low-energy diet. This finding suggests that part of this T difference can be related to internal ruminal (microbial) heat production (HP). The sequence of changes of parameters following exposure to a short heat load was compared to that during natural estrus: Whereas during estrus a simultaneous rise of HR, RR and T was evident, when a cow was exposed to heat load, its first response was to increase its HR considerably and later the HR was decreased to a level lower the initial one, simultaneously with sharp increase of RR and moderate increase of T, which was interrupted by T drops due to frequent drinking. We suggest that the first response of an animal to heat load was to increase blood fluxes to the skin to increase heat dissipation from the skin. When this mechanism was not sufficient, HR was decreased as a result of animals' effort to reduce internal HP, and RR was increased to increase evaporative heat dissipation from the lungs.

Poster Presentation No 42 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

INDIVIDUAL VARIABILITY FOR THERMAL REGULATORY MODELS USING MONTE CARLO SIMULATIONS

Miyo Yokota, Larry Berglund, and Gaston Bathalon U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA E-mail: Miyo.Yokota@us.army.mil Background: Current thermo-physiological simulation models are relatively accurate in predicting thermal responses of the average person of specified height, weight and % body fat. However, they lack the ability to predict the responses of a specific population or group without having individual anthropometric information. For a certain thermal stressful situation, what fraction of the group will experience thermal related illnesses? Monte Carlo (MC) randomization using the group mean ( ) and standard deviation (SD) of relevant data is a popular approach to identify and predict the trends of outcomes among individuals. However, the previous MC application to a thermal regulatory model was variable-independent (VI), namely, anthropometric dimensions for model inputs were treated as independent, although they are not completely independent in

• reality. In this study, a new MC approach, variable-dependent (VD) MC, was proposed and the effects of

simulated individual anthropometric variability on a thermo-regulatory model were examined. Method: VDMC simulations were developed based on a correlation matrix and and SD of anthropometric data. One hundred individuals were simulated by VI and VD MC methods using height ( ± SD: 177 ± 7 cm), weight (81 ± 12 kg), and body fat (17 ± 6%) from a 2004 US Army anthropometric database of males. Principal component analysis (PCA) was used in each MC method to examine the anthropometric distributions. The extreme anthropometric values identified in PCA were applied to a thermo-regulatory model to examine core temperatures (Tcr) to simulated heat stress (walking at 1.34 m/s in 40ºC, 38%RH environment). Results: The first PC (PC1) result generated by VI MC identified a football player body type (i.e., short-lean with heavy body weight). Conversely, the PC1 result in VDMC identified an overall body size (tall-fat, vs. short-thin), which was similar to the distribution from the original 2004 database. Different multivariate anthropometric distributions affected thermo-regulatory responses to simulated heat stress and heat tolerance levels to reach Tcr

• f 38.5 ºC were < 10 min differences between the two MC methods. Conclusions: Differences in

anthropometric dimensions generated by two MC methods affected physiological responses to simulated thermal stress in different ways. Thus, accurate representations of individual variability using VDMC approach can improve the performance of thermo-regulatory models.

Poster Presentation No 42 Day 2- July 24 (12:40-14:10) Day 3- July 25 (12:40-14:10)

MEASUREMENT OF THE CENTRAL VASOCONSTRICTION COEFFICIENT AND LOCAL AMPLIFICATION COEFFICIENTS FOR A MATHEMATCAL THERMOREGULATION MODEL

Frijns AJH1), Severens NMW1), van Marken Lichtenbelt WD2), Kingma BRM2), van Steenhoven AA1)

1) Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands 2) Department of Human Biology, Maastricht University, Maastricht, The Netherlands

Background: Many researchers have already attempted to model vasoconstrictionresponses, commonly using the mathematical representation proposed by Stolwijk (1971). They based the parameter values either on estimations or by attributing the difference between their passive models and measurement data. These methods are very sensitive for model errors. This study aims to present an independent method for determining physiological values in the vasoconstriction formulation. Procedure: An experimental protocol was developed to derive the local amplification coefficients and the transient vasoconstrictor tone directly. Ten young, healthy, male subjects participated in a cooling experiment. They were wearing standard clothing consisting of underwear (0.04 clo), a pair of short trousers (0.06 clo) and a t-shirt (0.09 clo) and were in a semisupine position for 3.5 hours. During the first 90 min. the room temperature was kept at 27oC (thermoneutral) for

• stabilizing. Then, it was lowered to 20oC. During the experiment, core temperature, skin temperatures, and skin

perfusion were measured. Results: From fingertip-lower arm gradients, it was seen that vasoconstriction started around t=90 min and lasted till the end of the experiment. For this period an exponential fit between blood perfusion and local skin temperatures were made. From these fits the central vasoconstriction coefficient and the local amplification coefficients were derived. Comparison with literature values showed that the estimated values of Stolwijk (1971) and the values mentioned by Tanabe et al. (2002) were comparable with

• ur measured values, but the values of Gordon (1974) and Fiala et al. (2001) differed a lot. When we put our

coefficients in our thermophysiological model ThermoSEM, we were able to predict successfully the temperatures in healthy persons as well as in patients undergoing surgery under normothermic and moderate hypothermic conditions. Conclusion: We developed a method to measure the central vasoconstriction tone and the local amplification coefficients directly. With these values we were able to predict temperature distributions in healthy persons as well as in patients undergoing surgery.