Differences in the secretion of pregnane compounds by follicular polycystic ovaries of androgen-sterilized rats and by normal preovulatory ovaries of early prooestrous rats were compared. Some rats were injected i.v. with LH 30 min before bleeding, in order to stimulate the secretion of steroids. This injection of LH greatly increased the secretion of progesterone, 5α-pregnane-3,20-dione and 3α-hydroxy-5α-pregnan-20-one by both types of ovaries. The response of the two progesterone metabolites in the polycystic ovaries was low, suggesting low 5α-reductase activity.
Because it is known that the preovulatory LH surge is absent in androgen-sterilized rats, a classical approach was taken to circumvent the probable deficit in cyclic release of LH by giving an i.v. injection of LH (25 μg) every 4 days for 16 days. Ovarian venous blood was collected 4 days after the last injection. The mean secretion of 5α-pregnane-3,20-dione and 3α-hydroxy-5α-pregnan-20-one from the ovaries of such androgen-sterilized rats became much (P <0·01) higher than that of multiple saline-treated controls. These results suggest that low 5α-reductase activity of polycystic ovaries in androgen-sterilized rats may be due to the absence of cyclic release of LH from the pituitary gland.
J. Endocr. (1986) 110, 507–510