Bombesin-induced hypothermia in food-deprived rats

Three separate experiments were conducted to characterize the effects of bombesin on core body temperature in food-deprived rats and further evaluate the role of food deprivation in this response. Previous research has demonstrated that naloxone reverses bombesin-induced hypothermia in cold-exposed rats. The present study was unable to demonstrate a similar reversal under conditions of food deprivation following naloxone. In a second experiment, cold exposure (11 degrees C) was shown to potentiate bombesin-induced hypothermia in food-deprived rats. Taken together, these data support the notion that bombesin-induced hypothermia in food-deprived and cold-exposed rats represent the activation or disruption of different thermoregulatory mechanism(s). The final experiment evaluated the effects of bombesin microinfusion into the preoptic area of the anterior hypothalamus on core body temperature. Animals were tested under conditions of food satiation, food deprivation, and insulin pretreatment. Bombesin produced hypothermia in food-deprived and insulin-treated rats. No hypothermia was observed in food-satiated rats. Our finding supports the notion that factors associated with the fasting state are important for the production of hypothermia by bombesin in food-deprived rats.