Stimulatory effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on insulin and glucagon release from the isolated perfused rat pancreas

Abstract

Rat pancreas perfusion was performed to study the effects of pituitary adenylate cyclase activating polypeptide (PACAP) on pancreatic hormone release. Under the perfusate glucose concentration of 5.5 mmol/l, 0.1 nmol/l PACAP27 significantly stimulated both insulin and glucagon release. The degree of stimulation was in a dose dependent manner. The stimulation of insulin release was clearly dependent on the perfusate glucose concentration, when compared with 2.8, 5.5 and 8.3 mmol/l. The potency of PACAP38 on the stimulation of insulin release was greater than that of PACAP27 at 5.5 mmol/l of perfusate glucose concentration, but not at 8.3 mmol/l. No differences for glucagon and cAMP release were found between the two peptides. PACAP's stimulatory effects on insulin and glucagon release were completely abolished by an equimolar and ten times lower concentration of somatostatin, respectively. The physiologic significance of these potent effects of PACAP's islet hormones release must be clarified by further studies.