NICOTINAMIDE, A POLY (ADP-RIBOSE) SYNTHETASE INHIBITOR, AMELIORATES B-CELL FUNCTION IN PARTIALLY DEPANCREATIZED RATS

we studied the effect of nicotinamide, a poly (ADP-ribose) synthetase inhibitor, on B-cell functions in 7-week-old male Wistar rats after 90 % pancreatectomy (Px). Nicotinamide (0.5 g/kg body wt.) was injected o nce a day i.p. from 1 week before the surgery, and the injection was c ontinued for 12 weeks after Px. Plasma glucose levels were significant ly lower in Px rats treated with nicotinamide (NA rats) than in Px rat s without treatment. In in vitro experiments with perfusion of the iso lated pancreas, insulin secretion induced by 16.7 mM glucose was blunt ed in Px rats whereas insulin secretion induced by 19 mM arginine was increased. Nicotinamide treatment restored glucose-induced insulin sec retion to normal and partly suppressed the hyperresponse of insulin to arginine. In addition, nicotinamide partially restored the priming ef fect induced by 28 mM glucose. The insulin content of the perfused pan creas was slightly but significantly greater in NA rats than in Px rat s. Histological examination revealed fibrotic degeneration and degranu lation in the islets of Px rats, whereas the normal structure was reta ined in most islets of NA rats. These results suggest that nicotinamid e ameliorates islet function in partially depancreatized rats.