MICROINFUSION OF BOMBESIN INTO THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUS PRODUCES HYPOTHERMIA IN THE INSULIN-PRETREATED RAT

Bombesin-like peptides are widely distributed in the mammalian central nervous system and participate in the regulation of a variety of autonomic functions. Central injection of bombesin produces hypothermia at normal ambient temperatures, but onlyif the rat has been food-deprived or made hypoglycemic with insulin. Two experiments were conducted to reevaluate the impact of bombesin microinfusion into the hypothalamic paraventricular nucleus (PVN) on core body temperature and feeding behavior. In Experiment 1, bombesin (0.05 and 0.1 μg/1.0 μl) produced hypothermia, but not hypophagia, in rats (n = 5) preated with insulin (10 U/kg; IM). Since a similar response was observed in rats with injections sites adjacent to the PVN, a smaller injection volume was evaluated in Experiment 2. Hypothermia, but not hypophagia, was observed in rats (n = 5) preatreated with insulin following bombesin (0.024 and 0.05 μg/0.5 μ). Bombesin did not produce hypothermia in rats with injection sites outside on the PVN. These findings suggest that the PVN is a sensitive site for bombesin-induced hypothermia. © 1990.