title: Long-term suppression of reproductive function by a single dose of gonadotropin-releasing hormone antagonists in a sheep model.
abstract: 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.
authors.affiliation: Department of Obstetrics and Gynaecology, Centre for Reproductive Biology, University of Edinburgh, Edinburgh, Midlothian, United Kingdom. bulnes@inia.es
authors.forename: Antonio
authors.initials: A
authors.lastname: Gonzalez-Bulnes
authors.forename: Carlos J H
authors.initials: CJ
authors.lastname: Souza
authors.forename: Rex J
authors.initials: RJ
authors.lastname: Scaramuzzi
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Campbell
authors.forename: David T
authors.initials: DT
authors.lastname: Baird
mesh_terms: 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
chemical_list: D006727:Hormone Antagonists; D009842:Oligopeptides; C422362:inhibin A; D007987:Gonadotropin-Releasing Hormone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C084350:antarelix