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 relationship between heme oxygenase-2 (HO-2), which synthesizes carbon monoxide (CO), and neuronal nitric oxide synthase (nNOS), which generates nitric oxide (NO), in the autonomic nerves of the human ductus deferens and seminal vesicle.
Materials and Methods: Specimens of the ductus deferens and seminal vesicle were obtained during cancer surgery or vasectomy. HO-2 and nNOS were localized by indirect immunofluorescence. Additionally, the histochemical NADPH-diaphorase (NADPH-d) activity of NOS was demonstrated using a standard staining method and some modifications.
Results: Anti-HO-2 labeling stained virtually all nerve cell bodies in local 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 to stain positively for HO-2. Some of the HO-2-immunoreactive ganglion cells were also nNOS-positive, their proportion varying between individual ganglia but generally not exceeding 20%. Both enzymes were present in large adventitial nerve trunks. Only nNOS but no HO-2 was found in small intramuscular and mucosal nerve fibers. In both the ductus deferens and seminal vesicle, the highest density of nNOS-containing nerve fibers was in the lamina propria of the mucosa. A well-developed plexus of nNOS-positive nerve fibers was 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 muscle 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 ductus deferens and seminal vesicle.