Down-regulation of testicular androgen biosynthesis and LH receptor levels by an LHRH agonist: role of prolactin.
Inhibition of plasma prolactin levels by 2-bromo-alpha-ergocryptine (CB-154) caused a 60% decrease and potentiated the inhibitory effects of [D-Ala6,des-Gly-NH2(10)]LHRH ethylamide on testicular LH receptor levels. Animals treated with the LHRH agonist showed reduced plasma and testicular testosterone levels and elevated progesterone concentration. This progesterone rise was further increased in animals having high circulating prolactin levels but was  prevented by CB-154. These data demonstrate that: (1) treatment with the LHRH agonist induces a blockage in the steroidogenic pathway at a step between progesterone and testosterone and (2) prolactin levels to an apparent accentuation of this blockage reflected by higher progesterone levels.
D000728:Androgens / Q000096:biosynthesis*; D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006728:Hormones / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D011374:Progesterone / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D012669:Seminal Vesicles / Q000187:drug effects / Q000378:metabolism; D013737:Testis / Q000187:drug effects / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism
D000728:Androgens; D006728:Hormones; D011956:Receptors, Cell Surface; D007987:Gonadotropin-Releasing Hormone; D001971:Bromocriptine; D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone