Effect of inhibition of estrogen synthesis or blocking its receptors on male rabbit reproduction

Purpose: The present aimed to study the effects of tamoxifen and fadrozole on semen characteristics and fertility, besides we emphasized the relationship between brain estrogen and sexual behavior in male rabbits. Methods: Eighty rabbits allocated into four equal groups. The control injected with sesame oil; the second injected with estradiol; the third injected with tamoxifen and the fourth injected with fadrozole. Treatments done daily for 60 days. Ten rabbits from each group served artificial vagina for evaluation of semen and sexual behavior. The other ten served female rabbits for fertility test. Reproductive organ and brain weights recorded. Serum and testicular testosterone, serum and brain estradiol and testicular zinc and cholesterol levels assayed. Results: Tamoxifen caused decrease in all estimated parameters except it increased both sperm ab normalities percentage; testicular cholesterol content; time of reaction and time between two consecutive ejaculations. Fadrozole results were opposite to that of tamoxifen except it increased the time between two consecutive ejaculations and decreased brain estradiol level. Conclusion: Fadrozole may be improve male rabbits performance along with elevated testosterone evident highlighting the important played by testosterone in regulating male rabbit fertility and advocacy the postulate that testosterone effect is mediated in part by its aromatization to estradiol