Comparative analysis of behaviora thrmoregulation

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The body temperature of homeothermic animal is controlled by multiple autonomic and behavioral responses and thermoreceplors are distributed throghout the body. This multiple input-output system is regulated by the central nervous system, on the top of which the hypothalamus including the preoptic area is located. Even though neural mechanism of autonomic regulation is well understand, that of behavioral regulation is still unknown. In the present project, this question is analysed from the viewpoint of comparative physiology, In the first year, we developped an operant system used for the study for behavioral thermoregulation, an animal that is put into a cold or hot environment gets warm or cool reinforcements when it enters a specific area. A rat moves freely in the box and its location is monitored photoelectrically while its deep body temperature is monitored by a telemetry system. In heat-escape experiments a hot wind blows through the box and when the rat enters a reward zone th … More e wind is switched to cool one for a given period (typically 30 sec). Conversely, in cold-escape experiments a cold wind blows through the box and when the rat enters the reward zone the wind is switched to warm one. Experiments show that rats quickly learn to stay near the reward zone and move in and out of it periodically. This system is based on behavior more natural than lever-pressing and is suitable for use in neurophysiological studies of behavioral thermoregulation. In the second year, we analysed the effect of fastingn on behavioral body temperature regulation using the system developped in the previous-year. Fasting induced decrease in body temperature in the inactive phase in circadian Cycle, and cold escape behavior was enhanced during that period, while heat escape behavior was unchanged. Similar experiment was done in fish and birds. Fasting showed similar effect in birds but had no effect in fish. Fasting would modulate thermoregulalory behavior so that energy expenditure is reduced in homeothermic animals but not in poikilothermic animals. Less