Rat testis LH/hCG recptors and testosterone production after treatment with GnRH.
Adults male rats were implanted subcutaneously for 1, 2 or 4 days with Alzet osmotic minipumps, infusing synthetic gonadotropin-releasing hormone (GnRH) at a rate of 0.1 microgram/h. Plasma LH increased significantly, reaching a maximum after 2 days treatment. Plasma and testicular testosterone levels increased to a maximum in 1 day, and decreased gradually thereafter, reaching the control level by day 4. Testicular specific [125I]hCG binding decreased gradually during the treatment, being 57% of the controls by day 4. It is concluded that changes of physiologic magnitude in circulatory LH are able to induce a significant loss of testicular LH/hCG binding capacity. Furthermore, after a short stimulatory phase there is a lack of response in testicular steroidogenesis to the elevated LH levels.
D000818:Animals; D006063:Chorionic Gonadotropin / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects*; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis*
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone