LOCALIZATION OF NADPH DIAPHORASE AND VASOACTIVE INTESTINAL POLYPEPTIDE-CONTAINING NEURONS IN THE EFFERENT PATHWAY TO THE RAT CORPUS CAVERNOSUM

Objective: We examined the coexistence of nitric oxide synthase (NOS) and vasoactive intestinal peptide (VIP) in the efferent pathway to the rat corpus cavernosum. Methods: We used NADPH diaphorase (ND) histoch emical staining, a specific marker of neuronal NOS, in combination wit h retrograde axonal transport of True Blue (TB) and VIP immunohistoche mistry. Results: Many neurons were labeled by TB in the cavernous nerv e and the body of the major pelvic ganglion (MPG), and fewer neurons i n the pelvic nerve. In the cavernous nerve, about 90% of TB-labeled ef ferent neurons were ND positive, and about 80% in the body of the MPG and pelvic nerve. Besides, 60-80% of TB-labeled efferent neurons proje cting to the corpus cavernosum showed VIP immunoreactivity. VIP was co localized with NOS in 70-80% of neurons. Conclusions: These findings s uggest that most of the ND-positive nerves and terminals in the corpus cavernosum come from the MPG via the cavernous nerve and that NO play s an important role; it may act in combination with NO because most NO S-containing neurons simultaneously showed VIP immunoreactivity.