Effects of an Antiandrogen, Flutamide, on Oocyte Quality and Embryo Development in Rats Superovulated with Pregnant Mare’s Serum Gonadotropin1

Publisher Website
Google Scholar
Abstract
Increased oocyte degeneration in rats is associated with enhanced ovarian androgen secretion following superovulation with pregnant mare''s serum gonadotropin (PMSG). To determine whether androgens may be causally related to oocyte degeneration, we examined the effects of an antiandrogen, flutamide, on oocyte quality and embryo development after induction of superovulation with PMSG. Immature female Sprague-Dawley rats were used for two experiments. In the first experiment, the females received either 5 mg flutamide or vehicle alone 30 and 36 h after 40 IU PMSG and were killed at 48, 60 and 72 h. Although total number of oocytes was not significantly different between the two groups, flutamide significantly reduced the percentage of degenerate oocytes ovulated at all the time intervals examined (p < 0.01). In the second experiment, the females were given 4 IU PMSG (control) or 40 IU PMSG with either 5 mg flutamide or vehicle. The rats were mated and then killed on Days 2, 3, 4, and 5 of pregnancy. Compared to control, flutamide did not effectively prevent the early loss of preimplantation embryos nor the developmental retardation which took place in the vehicle-treated rats after Day 2. However, flutamide treatment was associated with a significant decrease in embryo degeneration and a significant increase in the percentage of cleaved embryos on Day 2 (p < 0.01). Compared to levels associated with the vehicle regimen, ovarian and/or serum androgen levels in the flutamide-treated rats significantly decreased at 60 h (p < 0.01) and on Day 2 (p < 0.05). These results provide further evidence that ovarian androgen hypersecretion preceding fertilization plays an important role in the perturbation of oocyte normality and embryo development following superovulation with PMSG in rats.