Localization of NADPH-diaphorase activity and NOS immunoreactivity in the pancreas of rat and dog

Abstract

To clarify the role of nitric oxide (NO) in the pancreas, we investigate the localization of NADPH-diaphorase activity and neuronal nitric oxide synthase (nNOS) immunoreactivity in the pancreas of the rat and dog. NADPH-diaphorase activity and nNOS immunoreactivity were identical in the neuronal element of both species. NADPH-diaphorase activity and nNOS immunoreactivity were localized in neurons and endothelial cells of vascular system. Numerous NADPH-diaphorase positive and nNOS immunoreactive fibers were observed around pancreatic ducts and arteries. A moderate number of NADPH-diaphorase positive and nNOS immunoreactive fibers were observed surrounding the acini of dog pancreas, but there were few of these structures in rat pancreas. The islets of the rat pancreas contained a moderate number of NADPH-diaphorase positive and nNOS immunoreactive fibers. However in the dog, these positive fibers were not detected inside the islets. In the rat pancreas, 85% of the ganglion cells showed NADPH-diaphorase staining. In the dog, however, 30-50% of the ganglion cells demonstrated NADPH-diaphorase activity. Although NADPH-diaphorase histochemistry did not show any positive staining in the islet cells of pancreas in either species, NOS immunocytochemical method demonstrated weak positive staining in the rat islet cells. These results indicate that NO may play an important role for the neuronal regulation of pancreatic exocrine and endocrine activities in both species, but in the species-specific manner.