Occurrence, distribution and origin of peptide-containing nerves of guinea-pig and rat male genitalia and the effects of denervation on sperm characteristics.

A systematic immunohistochemical and radio-immunological survey of the occurrence, distribution and origin of the peptidergic nerve supply in guinea-pig and rat male genitalia is presented. Neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), substance P and CGRP were detected in the genital organs of both species. The densities and distribution patterns of the peptidergic nerves were compared with those of the adrenergic nerves, as revealed by antibodies raised against dopamine-beta-hydroxylase (D beta H) and tyrosine hydroxylase (TH), and the general neuronal component, as revealed by antibodies raised against neurofilament proteins (NF). Bilateral transection of the hypogastric nerves, in the guinea-pig, resulted in a decrease of substance P-containing nerves in the vas deferens and of NPY-, PHI- and VIP-containing nerves in the seminal vesicle. Unilateral disconnection of the pelvic nerves caused a decrease of VIP, PHI, substance P and CGRP nerve supply in the ipsilateral vas deferens and cauda epididymidis in the guinea-pig. A marked reduction of noradrenergic and NPY-containing nerves was observed in the vas deferens and sexual accessory glands of rats, chemically sympathectomised by chronic injection of low doses of guanethidine. Conversely, increase of substance P and CGRP immunoreactivities were observed, particularly in the vas deferens. After guanethidine, the cauda epididymidis and vas deferens were distended with spermatozoa, suggesting paralysis of the ducts. Spermatozoa had a decreased percentage of attached cytoplasmic droplets, indicating prolonged retention in the ducts.