Effects of peripheral and central bombesin on feeding behavior of rats.

Intraperitoneal injections of tetradecapeptide bombesin (BBS) produced large, dose-related suppressions of liquid and solid food intake in rats, with threshold doses of 1--2 micrograms-kg-1. The feeding-associated behaviors of rats receiving BBS by this route at a test meal were normally sequenced, and several other observations suggested that the effect of BBS was specific and not due to malaise. The structurally related amphibian peptide litorin and the structurally related mammalian gastrin-releasing peptide (GRP) produced similar suppressions of food intake. The satiety effect of BBS administered intraperitoneally did not require the accumulation of food in the gut, the presence of intact adrenals, the abdominal vagus, or the release of cholecystokinin. When BBS and cholecystokinin were administered simultaneous, the suppressive effects on food intake were additive. Lateral cerebroventricular injections of BBS also produced large, dose-related suppressions of food intake, with a threshold dose of 100 ng per rat. The effect by this route, however, was not behaviorally specific: BBS produced equivalent inhibitions of food and water intake at every point on the dose-response curve, and produced a marked increase in grooming which dominated the behavioral display. Thus, (1) peripheral BBS is a putative satiety signal in the rat; (2) the class (endocrine, paracrine, or neural) and mechanism of this satiety action is not established; and (3) the differences in specificity and behavior following intraperitoneal and cerebroventricular routes indicate that peripheral BBS does not act solely via the cerebrospinal fluid to elicity satiety.