Blood concentrations and biological effects of androstanediols at the onset of puberty in the female rat.

Androstanediols are the major products of the immature rat ovary. About two-thirds are present in blood as sulfates. One of the sulfate conjugates was identified as 5 alpha-androstane-3 beta,17 beta-diol-3-monosulfate. This steroid effectively inhibits postcastrational LH elevation in a concentration in which it is present in blood. Other androstanediol sulfates examined were without this activity. In the immature rat, levels of 3 alpha- and 3 beta-diol decrease sharply before the first ovulation. In Wistar rats, PMSG-treatment induced a similar decline in these steroids. When ovulation in PMSG-treated rats was blocked by pentobarbitone, the LH-surge and the decline of the 3 alpha- and 3 beta-diols was delayed. Thus, it seems that the decline in the blood concentration of the diols depends on the first LH surge.