The role of bombesin and bombesin-related peptides in the short-term control of food intake.

Bombesin (Bn) is a 14-amino acid peptide isolated from the skin of the frog Bombina bombina. The mammalian homologs of this peptide include three forms of gastrin-releasing peptide (GRP): GRP-10, GRP-27, and GRP-29, and a 10-amino acid peptide referred to as neuromedin-B (NMB). These peptides evoke a number of responses, including hyperthermia, bradycardia, inhibition of gastric emptying and inhibition of food intake, by activating one of three G protein-coupled receptors: an NMB-R or BB(1), a GRP-R or BB(2) and an orphan Bn receptor subtype-3 (BRS-3) or BB(3). Bombesin, GRP, and NMB have a role in the short-term control of food intake. These peptides reduce meal size (MS) and they prolong the intermeal interval (IMI), the time between the first and second meals. Studies have shown that the vagus and the splanchnic nerves in the upper gastrointestinal tract, which communicate with the feeding areas of the hindbrain, are necessary for reduction of MS and prolongation of the IMI by Bn, GRP, and NMB. In addition, one-tenth of the intraperitoneal dose of Bn, GRP, and NMB given in either the left gastric artery, which supplies the stomach, or the cranial mesenteric artery, which supplies the intestine, or the femoral vein, also reduces MS and prolongs the IMI. Thus, a potential neurocrine or an endocrine mode of action for these peptides requires further investigation.