The anti-progestin CDB 2914 has no antifertility effect in male rats

This study examines the effect of an anti-progestin (CDB 2914) with antiprogestational potencies similar to RU 486 on spermatogenesis, sperm maturation, and fertility in male rats. Adult male rats of proven fertility were administered the anti-progestin (10 mg/kg/day) or vehicle (control group) for 14, 35, and 70 days to study the possible effect of this compound on epididymal sperm maturation, post-meiotic sperm development, spermatogenesis, and fertility, respectively. Fertility rates of the rats were determined by mating studies. The anti-progestin, CDB 2914, had no effect on testis or accessory organ weights, epididymal sperm content or motility, testicular sperm count, spermatogenesis, and fertility of male rats. This study suggests that anti-progestins, when administered even at higher doses than those used in humans, have no contraceptive effect in adult male rats.