Plasma concentrations of free 5 alpha-androstane-3 alpha, 17 beta-diol and related gonadal steroids during spontaneous and induced sexual maturation in the female rat.
Plasma concentrations of free 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol), 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol), 5 alpha-dihydrotestosterone (DHT) and of testosterone (T) were determined in female rats undergoing spontaneous sexual maturation or pregnant mare's serum gonadotropin (PMSG)-induced precocious ovulation. In the prepubertal period, 3 alpha-diol levels showed an inverse relationship with uterine weights and a significant drop between Days 21 and 26 of life. Postpubertally, 3 alpha-diol concentrations tended to rise again, to a lesser degree, in parallel with increments in plasma T. Concentrations of 3 alpha-diol were increased tenfold 48 h after the administration of PMSG, i.e., at a time when T and estradiol-17 beta also peaked. Concentrations of 3 beta-diol and DHT remained low throughout both experiments. In earlier studies, it was found that exogenous 3 alpha-diol suppresses reproductive function in the immature rat, but the high concentrations of endogenous 3 alpha-diol reported here for the PMSG model clearly do not interfere with ovulation. The observed constellations of plasma steroids are compatible with the postulate of a peripubertal shift in ovarian progesterone metabolism from 5 alpha-reduced C21 steroids to delta 4-3-ketosteroids.
D015113:Androstane-3,17-diol / Q000097:blood*; D000732:Androstanols / Q000097:blood*; D000818:Animals; D013196:Dihydrotestosterone / Q000097:blood; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D009929:Organ Size; D010053:Ovary / Q000254:growth & development; D010062:Ovulation Induction; D010902:Pituitary Gland / Q000254:growth & development; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation / Q000187:drug effects; D013739:Testosterone / Q000097:blood; D014599:Uterus / Q000254:growth & development
D000732:Androstanols; D006064:Gonadotropins, Equine; D013196:Dihydrotestosterone; D015113:Androstane-3,17-diol; D013739:Testosterone