Bombesin is a peptide, originally isolated from the skin of the European fire-bellied toad, with pressor and sympathoexcitatory activity. Its three receptors are distributed throughout the central and peripheral nervous system and are involved in gastric acid secretion, emotional response, temperature control, learning, and memory. Neuromedin B and gastrin-releasing peptide (GRP) are mammalian homologs of bombesin. ICI 216140 is a GRP/bombesin receptor 2 antagonist (IC50 = 2 nM in vitro). At 2 mg/kg, it can reduce bombesin-stimulated pancreatic amylase secretion in rats. At 1 mM, it has been shown to attenuate bombesin-stimulated increases in blood pressure in rats.
