Periovulatory changes in serum concentration and ovarian content of 5 alpha-androstane-3 alpha, 17 beta-diol in the adult rat.

The high amounts of 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) present in immature female rats decline towards first ovulation, but on the day of first proestrus a peak is seen. This raises the possibility that during adulthood similar proestrous peaks may occur. Therefore, serum concentrations and ovarian content of 3 alpha-diol were estimated every two hours between 0900 and 2100 h in adult cyclic rats on the day of proestrus.

Changes in ovarian steroidogenesis in prepuberal rats induced to ovulate by low doses of human chorionic gonadotrophin.

To determine whether the decrease in ovarian 5 alpha-reduced androgen production before first ovulation might be caused by an increase in serum LH, prepuberal female rats were injected at 28-31 days of age with low doses of human chorionic gonadotrophin (hCG) (0.05-0.075 i.

Ovarian steroid concentrations in rats with spontaneous and with delayed or advanced ovulation.

The present study examined the ovarian progesterone levels in rats during the normal 5-day oestrous cycle and in rats with an experimentally induced delayed or advanced ovulation. Ovarian androgen and oestrogen concentrations were also studied in rats with an advanced ovulation. The ovarian progesterone concentrations during the normal cycle showed two peaks: one during metoestrus and dioestrus 1 and the second during the afternoon of pro-oestrus.

Androgen and oestrogen concentrations in the ovary of the cyclic rat.

In the 5-day cyclic rat the ovarian androgen and oestrogen concentrations, measured by radioimmunoassay, started a gradual rise on the day of metoestrus, reaching maximal values in the period from 22.00 h on dioestrus 2 until 17.00 h on the day of pro-oestrus.

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.