title: Effect of gonadotropin-releasing hormone antagonist on ovarian and uterine weights in immature female rats.
abstract: The immature rat uterotrophic assay has been proposed as a screening test method for detecting estrogenic and antiestrogenic chemicals. Although the immature rat uterotrophic assay is advantageous because the test animals are not traumatized by the ovariectomizing process, the effect of endogenous estrogen on ovarian and uterine weight in the immature animals that are used in immature rat uterotrophic assay has not received much attention. In this study, 19-day-old rats were treated with antide, a gonadotropin-releasing hormone antagonist, antide, to block gonadal production of endogenous estrogen. Uterine and ovarian weights of the antide-treated animals were markedly lower than those of control animals. This finding suggests that endogenous gonadal estrogen may already be acting on the uterus and ovaries in immature rats. Blocking endogenous estrogen with a gonadotropin-releasing hormone antagonist may enhance the sensitivity of the immature rat uterotrophic assay; however, the possibility that this protocol may interfere with the ability of the immature rat uterotrophic assay to detect centrally-mediated effects can not be discounted.
authors.affiliation: Chemicals Assessment Center, Chemicals Evaluation and Research Institute, 3-822 Ishii-machi, Hita-shi, Oita 8770061, Japan. takeyoshi-masahiro@ceri.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takeyoshi
authors.forename: Masakuni
authors.initials: M
authors.lastname: Sawaki
authors.forename: Shuji
authors.initials: S
authors.lastname: Noda
authors.forename: Takako
authors.initials: T
authors.lastname: Muroi
authors.forename: Kanji
authors.initials: K
authors.lastname: Yamasaki
mesh_terms: D000818:Animals; D001681:Biological Assay; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors*; D006727:Hormone Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D007279:Injections, Subcutaneous; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D010053:Ovary / Q000187:drug effects* / Q000254:growth & development; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation; D013047:Specific Pathogen-Free Organisms; D014599:Uterus / Q000187:drug effects* / Q000254:growth & development
chemical_list: D006727:Hormone Antagonists; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; C057022:iturelix