Reciprocal inhibition of the long-acting luteinizing hormone releasing hormone agonist Buserelin and human chorionic gonadotropin in stimulating Leydig cell steroidogenesis.
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.
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
D006063:Chorionic Gonadotropin; D012739:Gonadal Steroid Hormones; D006908:Hydroxyprogesterones; D013739:Testosterone; D004958:Estradiol; D019326:17-alpha-Hydroxyprogesterone; D002064:Buserelin