title: Antireproductive effects of a potent GnRH antagonist in the female rat.
abstract: The administration of the potent gonadotropin-releasing hormone antagonist [Ac-dehydro-Pro1,pCl-D-Phe2,D-Trp3,6,N alpha MeLeu7]GnRH (Antag) to female rats results in disruption of the estrous cycle and gestation. Daily doses of 200 microgram Antag are completely effective in blocking regular cycles, which resume 6-9 days after cessation of treatment. When administered to mated female rats, Antag seems to be less effective in terminating pregnancy during the earlier (1-7 days) than later (7-12 days) days of gestation. This may reflect the inability of Antag to lower the secretion of PRL (the luteotropic hormone of early pregnancy) as compared to the Antag-induced inhibition of LH production (the luteotropic hormone of midpregnancy). As a result, administration of Antag 7-12 days after mating is accompanied by a decrease in plasma progesterone levels incompatible with the survival of the embryos. These data provide further evidence that the neutralization of the function of endogenous gonadotropin-releasing hormone is deleterious to reproductive integrity.
mesh_terms: D000818:Animals; D002369:Castration; D004971:Estrus / Q000187:drug effects; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000031:analogs & derivatives; D010060:Ovulation / Q000187:drug effects; D010905:Pituitary Hormone Release Inhibiting Hormones / Q000494:pharmacology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D051381:Rats; D013997:Time Factors
chemical_list: D010905:Pituitary Hormone Release Inhibiting Hormones; D007987:Gonadotropin-Releasing Hormone; C026872:GnRH, (Ac-dehydro-Pro(1)-4-Cl-Phe(2)-Trp(3,6))-N-(alpha)-MeLeu(7)-