Role of androgens in hCG-induced ovulation in PMSG-primed immature rats

Abstract

Abstract. The effect of pre-treatment with the anti-androgens, cyproterone acetate (C.A.) and Flutamide (Fl) on hCG-induced ovulation in immature PMSG-primed rats was studied. The results showed that pre-treatment with either anti-androgen reduced the ovulation rate by 50%. Not all pre-ovulatory follicles (≥ 600 μm in diameter) in control and anti-androgen-treated rats ovulated in response to hCG. In control rats, hCG induced cumulus cell dispersement and resumption of meiosis in the ova of these non-ovulatory follicles; while C.A. or Fl treatment prevented these pre-ovulatory responses (P < 0.05). In a subsequent study, PMSG-primed rats were pre-treated with Fl and autopsied 8 h after hCG. In control rats, hCG reduced ovarian oestradiol content, did not alter ovarian testosterone content, increased ovarian progesterone content (P < 0.05) and increased the percentage of follicles with 3B-HSD activity within their granulosa cell layers (P < 0.05). Fl did not alter ovarian steroid content but blocked the hCG-induced appearance of 3B-HSD activity in the granulosa cells of pre-ovulatory follicles. This lack of 3B-HSD activity could result in a local decrease in progesterone within the non-ovulatory follicle. It appears that androgens, presumably synthesized in the theca interna play an important role in either ovulation or in maintaining responsiveness of the pre-ovulatory follicle to LH.