PARTIAL SYMPATHETIC DENERVATION OF THE RAT EPIDIDYMIS PERMITS FERTILIZATION BUT INHIBITS EMBRYO DEVELOPMENT

The rat cauda epididymidis receives sympathetic innervation from the i nferior mesenteric ganglion (IMG). We have previously demonstrated tha t surgical removal of the IMG and proximal hypogastric nerves (IMG den ervation) results in significant and cauda-specific changes in epididy mal sperm transport, sperm motility, luminal fluid protein composition , and tissue histology. In the present study we used natural mating tr ials and intrauterine insemination (IUI) techniques to determine wheth er or not IMG denervation affects male fertility and reproductive capa city. For the initial studies, adult male Sprague Dawley rats were mat ed with estrous females 1 and 4 weeks following IMG denervation. Nine days after mating, uterine implantation sites and corpora lutea (CL) w ere counted. In females mated with sham-operated control males, 85.8% of ovulated oocytes were fertilized and subsequently implanted. In con trast, females mated with IMG-denervated males 1 or 4 weeks following surgery had 0% and 3.5%, respectively, of ovulated oocytes fertilized and implanted. For rats maintained 21 days after mating, an average of 13 +/- 1 pups were delivered by each of nine females mated with sham- operated control male rats; whereas, only seven morphologically normal pups were delivered by one of 14 females mated with IMG-denervated ma le rats. Additional experiments demonstrated that the decrement in off spring was, in part, due to a significant decrease in the number of sp ermatozoa in the female uterus following mating with IMG-denervated ma les. To determine whether IMG denervation exerted an additional effect directly on the fertilizing ability of spermatozoa, IUI experiments w ere performed. Six million cauda epididymal spermatozoa from 1- or 4-w eek IMG-denervated males were inseminated into the uterine horns of lu teinizing hormone-releasing hormone (LHRH)-synchronized females and 9 days later implantation sites and CL were counted. Implantations were observed for 78%, 28%, and 25% of ovulated oocytes following IUI with spermatozoa from sham-operated controls and from 1- and 4-week IMG-den ervated rats, respectively. To determine whether the reduction in impl antation sites following IUI with spermatozoa from IMG-denervated rats resulted from impaired oocyte fertilization, studies were performed i n which oocytes were retrieved and stained 24 hours after IUI. Compara ble fertilization rates of 76.5% and 89.0% were observed using cauda e pididymal spermatozoa from IMG-denervated and sham-operated control ma les, respectively, indicating that oocyte fertilization was not affect ed by the loss of innervation. These studies establish the importance of innervation from the IMG for ejaculatory competence and sperm repro ductive capacity in the male rat. These data further suggest that symp athetic innervation in the epididymis critically influences paternal f actors associated with embryonic development.