Chronic effects of [D-Trp6-Pro9-NEt]luteinizing hormone-releasing factor on reproductive processes in the female rat.
LRF and one of its highly potent analogs, [D-Trp6-Pro9-NEt]LRF (A), were tested for their effects on pregnancy. Daily doses of A prevented implantation and/or caused resorption of implanted blastocysts in mated female rats. This effect was dose related and was most evident when given in regimens including days 5-7 or days 9-10 or pregnancy. LRF also has antigonadal effects, but at much higher doses than A. The use of corn oil vs. 0.1% gelatin-saline improved the effectiveness of low doses of A. Termination of pregnancy in A- or LRF-treated rats is most probably due to the markedly diminished progesterone secretion, which could result from the secretion of biologically inactive gonadotropins, reduced pituitary responsiveness to endogenous LRF, or down-regulation of gonadal receptors for LH.
D000818:Animals; D004971:Estrus / Q000187:drug effects; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D051381:Rats; D012098:Reproduction / Q000187:drug effects*
D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D007986:Luteinizing Hormone