Lateral hypothalamic injection of bombesin decreases food intake in rats

The effect of lateral hypothalamic injections of bombesin on feeding behavior was examined. Rats equipped with stainless steel cannulas directed toward the lateral hypothalamus received bilateral injections of bombesin prior to access to a liquid test diet after a 3 hr food deprivation. Bombesin in doses of 5 ng, 50 ng and 100 ng produced significant reductions in the size of the first meal. Injection of 50 ng of the biologically weak analogue [D-Trp8] bombesin had no effect. Injection of 5 ng or 50 ng of bombesin had no effect on deprivation-induced water intake, and injection of 50 ng of bombesin had no effect on body temperature. The food and water intake data and direct quantitative behavioral measures indicated that lateral hypothalamic injections of bombesin specifically reduced food intake. The structure-activity relationship for this effect was similar to those for other actions of bombesin. A bombesin-like peptide in the lateral hypothalamus or its receptors may play a role in postprandial satiety.