1. Gastrin-releasing peptide, a newly isolated mammalian peptide similar in its structure and actions to the amphibian peptide, bombesin, has recently been localized to nerves in the brain, gut and pancreas. The present study investigates its effects on gut and pancreatic peptides in man.
2. Intravenous infusion of 0.7 and 2.9 pmol min−1 kg−1 produced significant elevation of plasma gastrin, cholecystokinin-like immuno- reactivity and neurotensin. It was found also to potentiate glucose-dependent insulin secretion.
3. Its specific location in nerve fibres in the proximal gut and pancreas and its selective effect on gastroenteropancreatic peptides may favour its role as a physiological regulatory neuropeptide.