Doses of 100 or 200 micrograms of a novel GnRH antagonist ([N-acetyl-D beta Na11-D-pCl-Phe2-D-Phe3-D-Arg6-Phe7-Arg8-D-Ala10]NH2 GnRH) (4 animals/dose) were administered on Days 10/11 of the luteal phase and induced a marked suppression of circulating bioactive LH and progesterone concentrations within 1 day of treatment (P less than 0.01). Thereafter, progesterone concentrations remained low or undetectable until after the next ovulation. Similar results were obtained when 200 micrograms antagonist were given on Days 5/6 of the luteal phase (N = 4). The interval from injection of antagonist (200 micrograms but not 100 micrograms) to ovulation (based on a rise in progesterone above 10 ng/ml) was significantly longer than that from prostaglandin-induced luteal regression to ovulation in control cycles (N = 4/treatment) (range, 13-15 days after antagonist vs 8-10 days after prostaglandin, P less than 0.01). This delay of 4-5 days was equivalent to the duration for which LH concentrations were significantly suppressed by 200 micrograms antagonist when administered to ovariectomized animals (N = 3). Corpus luteum function during the cycle after GnRH antagonist treatment appeared normal according to the pattern of circulating progesterone. These results show that corpus luteum function and preovulatory follicular development in the marmoset monkey are dependent on pituitary gonadotrophin secretion.
is now at the Deutsches Primatenzentrum, Kellnerweg 4,3400 Gottingen, Federal Republic of Germany. Address reprint requests to him there. 0 1992 Wiley-Liss, Inc. 168 I Hodges et al.(hFSH) in vitro. Follicular development beyond 1 mm was inhibited by GnRHa treatment (preovulatory follicles normally 2-4 mm) although granulosa cell responsiveness to FSH during 48 h r of culture was not impaired. These results suggest that the GnRHa-induced suppression of follicular development and ovulation was mediated primarily by an inhibition of pituitary gonadotropin secretion and not by a direct action at the level of the ovary.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.