RAT EPIDIDYMAL SPERM QUANTITY, QUALITY, AND TRANSIT-TIME AFTER GUANETHIDINE-INDUCED SYMPATHECTOMY

Guanethidine, a chemical that selectively abolishes peripheral noradre nergic nerves, was used to investigate the role of sympathetic innerva tion in the maintenance of epididymal sperm quantity and quality. Four groups of 10 adult male rats each were treated daily for 21 days, by i.p. injections, with either 0 (saline vehicle), 6.25, 12.5, or 25 mg/ kg guanethidine. Norepinephrine content was reduced to undetectable le vels in the cauda epididymidis in all guanethidine groups after 3 wk o f treatment and was reduced to 7.4% of the control values after 1 wk o f 6.25 mg/kg treatment. While body weight gain was significantly decre ased at 12.5 and 25 mg/kg compared to that in controls, there was a si gnificant increase in the weights of the seminal vesicles/coagulating glands in all treated groups. The number of homogenization-resistant s permatids per testis and the daily sperm production per testis remaine d unchanged. The weight of the epididymis was significantly increased at 6.25 and 12.5 mg/kg. Moreover, the number of cauda epididymal sperm and the transit time were increased significantly at 6.25 mg/kg (10.2 days) compared to values in the control cauda (6.3 days). Neither ser um testosterone levels nor LH was affected in a dosage-related manner. There were no effects of guanethidine treatment on cauda epididymal s perm motility or morphology. A quantitative analysis of detergent-extr acted cauda epididymal sperm proteins by SDS-PAGE revealed no differen ces, but there were diminutions in seven proteins in homogenates of ca put/ corpus tissue. Histologic analysis of testis and epididymis secti ons revealed no differences between control and denervated animals. In a subsequent experiment the lowest effective dosage (6.25 mg/kg) was given to rats for 1 wk, and an increased number of cauda epididymal sp erm and a delay in sperm transit were observed. Our results indicate t hat low-dosage guanethidine exposure denervates the epididymis within 1 wk, thereby delaying epididymal transit; however, neither 1- nor 3-w k exposure produces qualitative changes in the sperm.