Comparative localization of heme oxygenase-2 and nitric oxide synthase in the autonomic innervation to the human ductus deferens and seminal vesicle

Purpose: The aim of present study was to determine the topographic relation ship between heme oxygenase-2 (HO-2), which synthesizes carbonmonoxide (CO) , and neuronal nitric oxide synthase (nNOS), which generates nitric oxide ( NO), in the autonomic nerves of the human ductus deferens and seminal vesic le. Materials and Methods: Specimens of the ductus deferens and seminal vesicle were obtained during cancer surgery or vasectomy. HO-2 and nNOS were local ized by indirect immunofluorescence. Additionally, the histochemical NADPH- diaphorase (NADPH-d) activity of NOS was demonstrated using a standard stai ning method and some modifications. Results: Andi-HO-2 labeling stained virtually all nerve cell bodies in loca l ganglia of the pelvic plexus, which is composed of a mixed population of postganglionic sympathetic and parasympathetic neurons supplying the pelvic viscera. Furthermore, nerve cell bodies in the wall of the seminal vesicle , which are considered an extension of the pelvic plexus, were also found t o stain positively for HO-2. Some of the HO-2-immunoreactlve ganglion cells were also nNOS-positive, their proportion varying between individual gangl ia but generally not exceeding 20%. Both enzymes were present in large adve ntitial nerve trunks; Only nNOS but no HO-2 was found in small intramuscula r and mucosal nerve fibers. In both the ductus deferens and seminal vesicle , the highest density of nNOS-containing nerve fibers was in the lamina pro pria of the mucosa. A well-developed plexus of nNOS-positive nerve fibers w as also observed in the muscular layer of the seminal vesicle. By contrast, there was a very sparse innervation by nNOS-positive nerve fibers in the m uscle coat of the ductus deferens. In addition, a population of epithelial cells in the seminal vesicle may contain an isoform of NOS, as revealed by a resistant NADPH-d activity. Conclusions: These findings set the scene for functional studies which will hopefully clarify the biological role of CO and NO in the control of the d uctus deferens and seminal vesicle.