title: Use of the immature rat uterotrophic assay for specific measurements of chorionic gonadotropins and follicle-stimulating hormones in vivo bioactivities.
abstract: The uterine weight growth stimulation by equine Chorionic Gonadotropin (eCG/PMSG) was found to occur at much lower eCG concentrations than ovarian growth. Human Chorionic Gonadotropin (hCG) which has only LH activity, was found to be as active as eCG in the uterotrophic assay whereas equine Luteinizing Hormone (eLH) which has dual LH+FSH activities like eCG, exhibited a much lower potency. In contrast to hCG, porcine and ovine LH as well as pFSH and oFSH exhibited no uterotrophic activity indicating that only gonadotropins with both LH activity and long half-lives are active alone in this assay. The FSH preparations were nevertheless found to trigger a dose-dependent response, but only in the presence of a subactive dose of hCG. The uterotrophic activity of hCG was found to be suppressed in ovariectomized immature rats and to be diminished after injection of GnRH antagonist suggesting an indirect pathway implicating the hypothalamo-pituitary complex. The data in this report together with the analysis of literature suggest that choriogonadotropins exert their stimulatory role on uterine growth by an indirect mechanism involving an increase in ovarian FSH receptors and FSH release by the pituitary. At the lowest concentrations of hCG, the increase in ovarian FSH receptors without endogenous FSH release is thought to be responsible for the sensitivity of the uterotrophic assay to exogenous FSHs. In conclusion, the immature rat uterotrophic assay is a sensitive and convenient assay for eCG and hCG as well as for FSHs in the presence of a sub-active dose of hCG.
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS), Unit Physiologie de la Reproduction et des Comportements, Nouzilly, France.
authors.forename: F
authors.initials: F
authors.lastname: Lecompte
authors.forename: E
authors.initials: E
authors.lastname: Harbeby
authors.forename: C
authors.initials: C
authors.lastname: Cahoreau
authors.forename: D
authors.initials: D
authors.lastname: Klett
authors.forename: Y
authors.initials: Y
authors.lastname: Combarnous
mesh_terms: D000818:Animals; D001681:Biological Assay; D006063:Chorionic Gonadotropin / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D004958:Estradiol / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D006207:Half-Life; D006736:Horses; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D010053:Ovary / Q000187:drug effects* / Q000254:growth & development; D051381:Rats; D017208:Rats, Wistar; D012756:Sheep; D013552:Swine; D014599:Uterus / Q000187:drug effects* / Q000254:growth & development
chemical_list: D006063:Chorionic Gonadotropin; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone