Effect of human chorionic gonadotropin on luteinizing hormone and prolactin binding by testes of bilaterally cryptorchid rats.
This study investigates the ability of the testis in the cryptorchid state to bind luteinizing hormone (LH) and prolactin (Prl). For this purpose, rats were made bilaterally cryptorchid at 21 days of age; sham-operated rats were used as controls. At 56 days, the animals were injected with saline or with increasing doses of human chorionic gonadotropin (hCG: 1, 10 or 100 IU) and killed 8 or 24 h after injection. Cryptorchidism and injection of hCG did not alter plasma Prl levels. In cryptorchid rats, both LH and Prl binding expressed in pmol/testis were lower than in sham-operated controls (about 75% and 65%, respectively), but unchanged (LH binding) or increased (Prl binding) when expressed in pmol/g testis. In controls, 100 IU hCG induced a significant decrease in LH binding at 24 h. Prl binding was also significantly lower in controls injected with 100 IU hCG than in those injected with 1 or 10 IU hCG, at 8 h. In cryptorchid rats injected with 100 IU hCG, the LH binding fell 8 h and 24 h after injection; at 24 h, hCG reduced Prl binding. In conclusion, there was a considerable decrease in LH and Prl receptors in the abdominal testes. The negative regulation of these receptors in response to hCG was maintained, but at times and for doses which differed from those observed in scrotal testes.
D000818:Animals; D006063:Chorionic Gonadotropin / Q000097:blood / Q000494:pharmacology*; D003456:Cryptorchidism / Q000378:metabolism*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D011974:Receptors, LH / Q000187:drug effects*; D011981:Receptors, Prolactin / Q000187:drug effects*; D013737:Testis / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D011974:Receptors, LH; D011981:Receptors, Prolactin; D011388:Prolactin