Influence of bombesin on threshold for feeding and reward in the rat

Bombesin's purported role in satiety mechanisms prompted this investigation of its effects on thresholds for stimulation-induced feeding and self-stimulation in the rat. Single electrodes were implanted in the lateral hypothalamus and the ability of each electrode to support self-stimulation and stimulation-induced feeding was evaluated at four current levels between 80 and 320 microA. The frequency thresholds associated with each current value were assessed following four intraperitoneal doses of bombesin, 2, 4, 8, and 16 micrograms/kg, as well as a saline dose. Bombesin increased the thresholds for stimulation-induced feeding at doses known to reduce food intake without influencing self-stimulation thresholds. From these findings we conclude that (1) the effects of peripheral bombesin on stimulation-induced feeding are analogous to its effects on normal feeding and (2) the data provide additional evidence for a pharmacological dissociation between stimulation-induced feeding and reward.