Long-term suppression of reproductive function by a single dose of gonadotropin-releasing hormone antagonists in a sheep model.
OBJECTIVE
To determine the effect of single long-acting doses of GnRH antagonists on reproductive function in a sheep model.


METHODS
Observational, model study.


METHODS
University-affiliated research unit.


METHODS
Nine intact mature Merino sheep in experiment 1 and 12 mature Merino-crossed ewes with the ovary autotransplanted to the neck in experiment 2.


METHODS
Synchronization of estrous cycle either with intravaginal progestins or prostaglandin F2alpha analogues and treatment with a single dose of GnRH antagonist; evaluation of reproductive activity, plasma sampling, and ovarian ultrasonography.


METHODS
Determination of estrus behavior; plasma concentrations of P, FSH, LH, and inhibin A; and number and size of ovarian follicles.


RESULTS
In both experiments, the concentrations of FSH and LH were suppressed when compared with those in control ewes. In experiment 1, the ovulatory cycles were suppressed for > or = 55 days in treated sheep. In experiment 2, there were no follicles sized > or = 5 mm in treated ewes for 50 days.


CONCLUSIONS
The suppression of the development of large follicles for > or = 30 days after a single injection of a long-acting GnRH antagonist provides a novel convenient method of pretreatment before COS.
Gonzalez-Bulnes
Antonio
A
Department of Obstetrics and Gynaecology, Centre for Reproductive Biology, University of Edinburgh, Edinburgh, Midlothian, United Kingdom. bulnes@inia.es
Souza
Carlos J H
CJ
Scaramuzzi
Rex J
RJ
Campbell
Bruce K
BK
Baird
David T
DT
D000818:Animals; D004971:Estrus / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors*; D006727:Hormone Antagonists / Q000494:pharmacology*; D007265:Inhibins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D009994:Osmolar Concentration; D006080:Ovarian Follicle / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010060:Ovulation / Q000187:drug effects; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects*; D012756:Sheep; D013997:Time Factors
D006727:Hormone Antagonists; D009842:Oligopeptides; C422362:inhibin A; D007987:Gonadotropin-Releasing Hormone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C084350:antarelix