Autonomic and behavioural thermoregulation in starved rats

• Published in: The Journal of physiology 2000-07, Vol.526 (2), p.417-424
• Main Authors: Sakurada, Sotaro, Shido, Osamu, Sugimoto, Naotoshi, Hiratsuka, Yasuhiro, Yoda, Tamae, Kanosue, Kazuyuki
• Format: Article
• Language: English
• Subjects: Animals; Autonomic Nervous System - physiology; Autonomic Nervous System - physiopathology; Body Temperature Regulation - physiology; Circadian Rhythm; Food Deprivation; Hypothermia - etiology; Hypothermia - physiopathology; Male; Original; Rats; Rats, Wistar; Starvation - physiopathology; Temperature
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1111/j.1469-7793.2000.00417.x

We investigated the mechanism of starvation-induced hypothermia in rats. Threshold core temperatures ( T cor ) for tail skin vasodilatation and cold-induced thermogenesis were determined after a 3 day starvation using a chronically implanted intravenous thermode. Food deprivation significantly lowered the threshold T cor for heat production, but did not affect the heat loss threshold. Thermogenic response to a fall in T cor below its threshold was enhanced by starvation. Preferred ambient temperatures ( T pref ) and T cor were measured before and during a 3 day starvation in a thermal gradient. The 3 day starvation significantly lowered T cor only in the light phase of the day. The level of hypothermia was the same throughout the fasting period, while T pref gradually increased during the 3 days of starvation. When rats were starved at a constant ambient temperature of 25°C (no thermal gradient), their T cor levels were comparable with those of the rats kept in the thermal gradient. The results suggest that, in rats, hypothermia caused by starvation was not due to a decrement in thermogenic capability, but was due to a decrease in the threshold for the activation of thermogenesis.