Effect of Vasopressin on Fertility of Male Rats

Abstract

Several drugs, which induce epididymal contractions, have been tested as potential male contraceptives. Vasopressin is one such agent, which has not been tested as a potential male contraceptive acting via epididymis. The aim of this study was to examine the effect of vasopressin on male reproductive competence using rats. Two doses of vasopressin (0.2 LU. and 0.4 IU.! rat) was injected daily to the cauda epididymides of rats for 7 consecutive days. These rats were individually paired with a receptive female on days 1,3 and 7 of treatment and on day 7-post treatment. The results show that both doses of vasopressin caused the production of oligozoospermic ejaculates. In addition, the higher dose induced marked teratozoospermia (decapitation of sperm heads). However, precoital sexual behavior and fertility of treated rats remained uninhibited. At autopsy, sperm granulomas were evident close to vaso-epididymal junction. The most likely cause for the production of vasopressin-induced oligozoospermia was the presence of sperm granulomas. In addition, ejaculatory dysfunction may playa role in the production of oligozoospermia, The possible cause for teratozoospermia is sperm toxicity.