Effect of gossypol on spermatozoal lactate dehydrogenase-X (LDH-X) in male rats

The studies in this report evaluate the inhibitory effects of long-term gossypol acetic acid (gossypol) administration on spermatozoal lactate dehydrogenase (LDH-X) activity, fertility and reversibility. Gossypol at 20 mg/kg/day or vehicle only was administered orally to adult male rats for 5 consecutive weeks. Groups of control and gossypol-treated rats were sacrificed at 2-, 4-, and 5-week intervals when LDH-X analysis of spermatozoa were prepared from the tail of the epididymis. An additional group of control and gossypol-treated rats were allowed to recover for up to 8 weeks after withdrawal of the treatment. In the gossypol-treated rats, the spermatozoal LDH-X activity was depressed by 80% of control level after a 5-week treatment period. There was no significant difference in spermatozoal LDH-X activity between the control and treated animals at 2 and 4 weeks. However, the number of ejaculated sperm estimated from the vaginal smear preparations after each mating was significantly less than the control values after 2, 4 and 5 weeks of treatment. At 5 weeks after the cessation of gossypol treatment, the spermatozoal LDH-X activity had only partially recovered but the fertility (number of ejaculated sperm, embryo implantation sites and pups born) had recovered to a level comparable to the control values 5 weeks after the cessation of gossypol treatment. The inconsistencies in the response of spermatozoal LDH-X activity, sperm number and fertility to gossypol may suggest that the antifertility action of gossypol and spermatozoal LDH-X activity in adult male rats may not be directly related as suggested by the results generated from the in vitro studies.