Is the postovulatory release of follicle-stimulating hormone in the rabbit mediated by luteinizing hormone-releasing hormone?
Studies were performed to determine whether the postovulatory secretion of FSH in the rabbit is an LHRH-mediated event. Does were mated and then injected at 12 and 18 h postcoitum with pentobarbital (30 mg/kg BW), an agent known to block endogenous LHRH release. The injection of this barbiturate had no measurable effect on the postovulatory FSH secretion pattern. Administration of the LHRH antagonist [Ac-D-p-C1-Phe1,2, Phe3, D-Arg6, D-Ala10]LHRH (0.5 mg/doe) prevented all gonadotropin release in response to LHRH injection (10 micrograms/kg BW). When this same dose of the antagonist was injected at 18 h postcoitum, the postovulatory FSH secretion pattern was unaffected. Finally, to prove that the pituitary was sensitive to LHRH at 18-h postcoitum, LHRH (10 micrograms/kg BW) was injected into rabbits mated 18 h earlier; this treatment led to a marked increase in FSH secretion showing that the pituitary is responsive to LHRH at this time. The results of this study show that two drugs which block LHRH-mediated gonadotropin release have no effect on the postovulatory secretion of FSH and support the concept that this episode of FSH secretion occurs via a pathway which does not include the hypothalamic secretion of LHRH.
D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010060:Ovulation; D010424:Pentobarbital / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects; D011817:Rabbits
D007987:Gonadotropin-Releasing Hormone; C037395:LHRH, N-Ac-(4-Cl-Phe)(1,2)-Phe(3)-Arg(6)-AlaNH2(10)-; D005640:Follicle Stimulating Hormone; D010424:Pentobarbital