title: Reciprocal inhibition of the long-acting luteinizing hormone releasing hormone agonist Buserelin and human chorionic gonadotropin in stimulating Leydig cell steroidogenesis.
abstract: The interference between human chorionic gonadotropin (hCG, Pregnyl, Organon 1500 IU i.m.) and the long acting LHRH agonist Buserelin (500 micrograms s.c.) in stimulating Leydig cell steroidogenesis was studied in 6 eugonadal men. Simultaneous administration of a single injection of the agonist (LHRH alpha) and hCG blunted the plasma testosterone response observed 24 h after LHRH alpha alone, enhanced the secretion of oestradiol without affecting 17-hydroxy-progesterone and aggravated the late steroidogenic block at the 17,20-lyase locus. As compared to hCG alone, combined LHRH alpha and hCG administration also decreased the maximum and 48 h testosterone increments and the testosterone production reflected by the area under the curve, enhanced the production of oestradiol and again aggravated the 17,20-lyase lesion. The data show that the long acting agonist LHRH alpha and hCG reciprocally inhibit their stimulatory effect on Leydig cell testosterone secretion probably by a suppressive effect of oestrogens on the conversion of C21- to C19-steroids. The mechanism underlying this reciprocal inhibition remains to be elucidated.
mesh_terms: D019326:17-alpha-Hydroxyprogesterone; D000328:Adult; D002064:Buserelin / Q000494:pharmacology*; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004958:Estradiol / Q000096:biosynthesis; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis*; D006801:Humans; D006908:Hydroxyprogesterones / Q000096:biosynthesis; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013739:Testosterone / Q000096:biosynthesis
chemical_list: D006063:Chorionic Gonadotropin; D012739:Gonadal Steroid Hormones; D006908:Hydroxyprogesterones; D013739:Testosterone; D004958:Estradiol; D019326:17-alpha-Hydroxyprogesterone; D002064:Buserelin