Effects of PYY and PP on endocrine pancreas

Novel intestinal polypeptide YY (PYY) and pancreatic polypeptide (PP) were infused in fed anaesthetized rats. The peptides (10 and 100 pmol/kg X min) were administered during 30 min, alone, together with glucose or together with arginine. Plasma concentrations of glucose, insulin and glucagon were measured. At the dose of 10 pmol/kg X min the peptides had no effect. PP at the dose of 100 pmol/kg X min slightly augmented basal, but had no effect on stimulated insulin and glucagon release. PYY at the dose of 100 pmol/kg X min was without effect on basal insulin and glucagon levels and on glucose-induced insulin release, but exerted an inhibitory effect on arginine-induced secretion of both insulin and glucagon. It is unlikely that PYY and PP can affect secretion of insulin and glucagon via blood circulation. The potential capability of high doses of PP to affect insulin and glucagon secretion suggests that this peptide may exert direct (paracrine) effects on the pancreatic A- and B-cells.