COLOCALIZATION OF NADPH DIAPHORASE REACTIVITY AND VASOACTIVE INTESTINAL POLYPEPTIDE IN HUMAN COLON

Nitric oxide-containing nervous structures were localized in the human colon using NADPH diaphorase activity and nitric oxide synthase immun oreactivity. We found some, solitary NADPH diaphorase-reactive and nit ric oxide synthase-immunoreactive neurons in the submucous plexus, whi le the myenteric plexus contained several neurons, often arranged in c lusters, and nerve fibers showing these markers. The circular muscle l ayer contained a dense plexus of NADPH diaphorase-reactive nerves, whi ch was greater than that in the longitudinal muscle layer. We report o n co-localization of NADPH diaphorase activity and VIP immunoreactivit y in several neurons of the myenteric ganglia. Such co-localization ha s not been reported previously for human colon. Localization Of nitric oxide synthase and VIP in the myenteric plexus and in the nerves of c ircular muscle layer raises the possibility that nitric oxide contribu tes to the regulation of motility in the human colon.