NADPH-DIAPHORASE IS COLOCALIZED WITH NITRIC-OXIDE SYNTHASE AND VASOACTIVE INTESTINAL POLYPEPTIDE IN RAT PANCREATIC NEURONS IN CULTURE

NADPH-diaphorase activity together with nitric oxide synthase- and vas oactive intestinal polypeptide-immunoreactivities were examined in the neurons of the rat pancreas in culture. Nitric oxide synthase (NOS)- and vasoactive intestinal polypeptide (VIP)-immunoreactivities were lo calized in a subpopulation of neurons which mere also NADPH-diaphorase positive. All neurons expressing colocalized activities for NOS/VIP a nd NADPH-diaphorase were solitary cells in culture. Each of these doub le-labelled neurons was characterized by a round or oval cell body, wi th short and long processes emanating from it. Some of these processes traversed several micrometres before terminating on the exocrine acin ar and endocrine cells. The present study provides evidence that nitri c oxide may act as a regulatory agent in the inhibitory neural control of the secretory functions in the pancreas, thereby maintaining the m ilieu interieur of the organism.