Injections of bombesin into the substantia nigra produce hypothermia and hypophagia in food-deprived rats.

Hypothermia and hypophagia have been elicited, under a variety of experimental conditions, by central injections of bombesin. The preoptic area of the anterior hypothalamus has been suggested as the active site for the hypothermia observed in rats exposed to cold, while the lateral hypothalamus has been implicated in the production of hypophagia induced by bombesin. Data are reported here demonstrating a significant, dose-related decrease in both intake of food and body temperature following microinjections of bombesin into the substantia nigra of male rats deprived of food for 18 hr. Similar injections into the preoptic area, the lateral hypothalamus and the ventromedial hypothalamus failed to produce a consistent decrease in either intake of food or body temperature. Although a decrease in body temperature was demonstrated following injections into the paraventricular nucleus of the hypothalamus, this decrease did not appear to be dose-related. Injections of bombesin at this site had no effect on food intake. The possibility of an underlying dopaminergic mechanism for the hypothermic and hypophagic effects of bombesin is discussed.