Bombesin-like receptors are widely distributed in the CNS as well as in the GI tract where they modulate smooth-muscle contraction, exocrine and endocrine processes, metabolism, and behaviour through the binding of bombesin-like peptides. They include gastrin-releasing peptide receptor (GRP-R), neuromedin B receptor (NMB-R) (Corjay MH et al, 1991) and bombesin-like receptor-3 (BRS-3) (Fathi Z et al, 1993). BRS-3 binds bombesin peptides with low affinity and is often classed as an orphan receptor. There are two homologues of bombesin-like peptides; Gastrin-releasing peptide (GRP) (Sausville EA et al, 1986) and Neuromedin-B (NMB) (Krane IM et al, 1988). GRP regulates gastric acid secretion and motor function and is a negative feedback operator regulating fear. NMB is involved in the regulation of many functions such as cell growth, body temperature and blood pressure and glucose levels.