title: [Desensitization by human chorionic gonadotropin (hCG): demonstration of a negative control of gonadotropin receptors by hCG at the level of testicular Leydig cells].
abstract: A single injection of hCG (500 IU) to intact and hypophysectomized prepubertal rat increases plasma testosterone levels and decreases hCG receptors in the testicular Leydig cells for 4 to 5 days. In intact animals testosterone exhibit a rapid increase within hours and a delayed paradoxical increase between 60 and 96 hours. In hypophysectomized animals the first peak is not present. In both intact and hypophysectomized rats hCG receptors are almost undetectable between 10 and 96 hours following hCG injection. Since receptor occupancy cannot account for this phenomenon it is concluded that hCG is exerting a negative control on its own receptors.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D007016:Hypophysectomy; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects* / Q000378:metabolism; D013739:Testosterone / Q000097:blood
chemical_list: D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D013739:Testosterone; D007986:Luteinizing Hormone
vernacular_title: Désensibilisation par la gonadotrophine chorionique humaine (hCG): mise en évidence d'un contrôle négatif des récepteurs des gonadotrophines par la hCG au niveau des cellules de Leydig du testicule.