MECHANISM OF INSULIN RELEASE INDUCED BY VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) AND GALANIN - STUDY ON THEIR INTERACTION IN ISOLATED PERFUSED RAT PANCREAS

It is known that both VIP and galanin are neuropeptides, which are present in nerves around the islet. VIP has an effect to stimulate insulin release, while galanin inhibits insulin release. In the present paper we examined the interaction between VIP and galanin on the release of insulin, glucagon and somatostatin in the isolated perfused rat pancreas. The possible involvement of cAMP in such interaction was also investigated. Various concentrations of galanin (10(-10)M, 10(-9)M and 10(-8)M) inhibited 10(-8)M VIP-induced insulin release dose dependently, but 10(-8)M galanin did not affect 10(-8)M VIP-induced release of glucagon and somatostatin. Galanin tended to inhibit cAMP release induced by VIP. Galanin inhibited 10(-5)M forskolin induced insulin and cAMP release. It is indicated that the interacion between VIP and galanin is partially involved in insulin release and such interaction is mediated by cAMP and not through an A-cell or D-cell paracrine effect.