Possible role of 5 alpha-androstane-3 alpha, 17 beta-diol in the control of follicle-stimulating hormone secretion in the immature female rat.

A possible role of 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-androstanediol) in the control of FSH secretion was studied at various ages in ovariectomized rats. In the rat strain used, vaginal opening, coincident with first ovulation, generally occurs between 37 and 42 days of age. If 3 alpha-androstanediol alone was given as an ovarian substitute, an inhibitory effect on FSH release was evident with all three doses tested (50, 100, 300 microgram/100 g body wt) between 13 and 30 days of age; at 33-35 days of age only the 300 microgram dose caused some inhibition of FSH release. Results were more complex if 3 alpha-androstanediol was given in combined treatment with oestradiol and progesterone. Given with progesterone, 3 alpha-androstanediol showed a synergistic inhibitory action on FSH release between 20 and 30 days of age. However, when 3 alpha-androstanediol was combined with oestradiol a clear decrease in effect, as compared to the effect of oestradiol alone, was found between 20 and 30 days of age. Also the effect of combined oestradiol and progesterone treatment was greater than the effect of combined treatment with oestradiol, progesterone and 3 alpha-androstanediol. At all ages after day 20 none of the steroid combinations tested was capable of maintaining FSH levels in ovariectomized rats similar to those in intact rats. It is concluded that 3 alpha-androstanediol might play a role in the control of FSH secretion in the immature rat, but after day 20 the potentially inhibitory action of 3 alpha androstanediol on FSH secretion is limited in the presence of oestradiol.