title: Comparison of the effects of two GnRH antagonists on LH and FSH secretion, follicular growth and ovulation in the mare.
abstract: The effects of two GnRH antagonists were tested in order to delay and/or synchronise ovulation in mares. Five mares received Antarelix (0.01 mg.kg(-1)), 5 mares received Cetrorelix (the same dose), 5 mares (control mares) received the vehicle intravenously, twice daily, for 8 days from the day the largest follicle reached 22 mm following prostaglandin administration. Ovulation was postponed in all mares injected with Antarelix (19.4 +/- 1.2 days after the beginning of the treatment) and in 2/5 mares injected with Cetrorelix (20 +/- 1 days) vs. 6.2 +/- 0.4 days in control mares. During the treatment, LH concentrations were strongly depressed in Antarelix and in Cetrorelix mares (1.6 +/- 0.1 and 3.8 +/- 0.5 ng.mL(-1) respectively vs. 21 +/- 2.5 ng.mL(-1) in control mares). In the 3 Cetrorelix mares which ovulated during the treatment. 2 initiated their LH surge at this moment. FSH concentrations were not affected in Antarelix or in Cetrorelix mares during the treatment (11.4 +/- 1.3 and 7.9 +/- 0.8 ng.mL(-1) respectively vs. 10.5 +/- 0.8 ng.mL(-1) in control mares). In conclusion, Antarelix seems more efficient than Cetrorelix for postponing ovulation in mares. The role of LH in antral follicular development before the preovulatory stage is confirmed.
authors.affiliation: Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, Nouzilly, France. dguillau@tours.inra.fr
authors.forename: Daniel
authors.initials: D
authors.lastname: Guillaume
authors.forename: Bernard
authors.initials: B
authors.lastname: Bruneau
authors.forename: Christine
authors.initials: C
authors.lastname: Briant
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology*; D006736:Horses; D007986:Luteinizing Hormone / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D006080:Ovarian Follicle / Q000502:physiology*; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology; D011897:Random Allocation
chemical_list: D006727:Hormone Antagonists; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C084350:antarelix; C062876:cetrorelix