Effect of ovariectomy on oestrogen-sensitive feedback elements.
Serum LH and FSH were determined by radioimmunoassay in untreated and oestrogen-treated ovariectomized rats.  The animals were sacrificed 7, 14, 21 and 28 days after ovariectomy.  Oestradiol benzoate was administered in the daily dose of 50 mug on the 2 days preceeding sacrifice.  It has been found that oestrogens exert a strong inhibitory effect on the release of LH, as evidenced by a decrease in serum titers of the hormone.  Oestradiol suppressed LH almost completely in animals with both low (7 or 14 days post-ovariectomy), and high levels of serum LH(21 or 28 days post-ovariectomy).  Oestradiol failed to totally suppress serum FSH at any post-castration time considered.  Moreover, the inhibitory effect of oestradiol on FSH release decreased as post-castration time increased.  These data suggest that the feedback mechanisms which control the secretion of LH and those which control the secretion of FSH are substantially different.
D000818:Animals; D002369:Castration; D003864:Depression, Chemical; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005246:Feedback; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D010053:Ovary / Q000502:physiology; D051381:Rats; D013997:Time Factors
D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone