Estrogen induces the release of luteinizing hormone-releasing hormone in normal cyclic women.
The plasma concentrations of immunoreactive LRH, LH, and FSH were determined by RIA every 6 h until 72 h after iv administration of conjugated estrogens during the midfollicular phase. The percentage change in LH from the preinjection level showed a biphasic pattern after the injection of conjugated estrogens, i.e. significant suppression (-70%) from 6-42 h after the injection, followed by a rebound increase with a peak (+150%) at 56 h. Plasma FSH after the injection also showed a biphasic pattern. The plasma immunoreactive LRH levels were unchanged until 32 h after the injection, but then increased significantly (P less than 0.02) to 160% of the preinjection level at 42 h and then decreased rapidly. These data indicate that 1) estrogen administration results in increases in plasma immunoreactive LRH and LH, and the peak of plasma LRH precedes that of gonadotropin; and 2) the negative feedback effect of estrogen on gonadotropin secretion may not be mediated through LRH.
D000328:Adult; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone / Q000097:blood*; D006801:Humans; D007275:Injections, Intravenous; D007986:Luteinizing Hormone / Q000097:blood*; D008598:Menstruation; D011863:Radioimmunoassay; D013997:Time Factors
D004966:Estrogens, Conjugated (USP); D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone