POTENT INHIBITORY ACTIVITY OF [D-LEU6, DES-GLY-NH21Q]LHRH ETHYLAMIDE ON LH/hCG AND PRL TESTICULAR RECEPTOR LEVELS IN THE RAT

Abstract
Injection of male rats with 40-200 ng of [D-Leu6, des-Gly-NH210]LHRH [luteinizing hormone-releasing hormone] ethylamide for 7 days caused a maximal 80% reduction of testicular LH/hCG [human chorionic gonadotropin] receptor level with 1 injection per day being as efficient as 3 daily injections. A similar inhibitory effect was observed on testicular PRL [prolactin] receptors. Testis and seminal vesicle weight and plasma testosterone levels were also significantly reduced by this treatment. A LHRH agonist, when given at a relatively low dose, is capable of reducing testicular LH/hCG and PRL receptor levels and testicular function, the effect being probably mediated by increased endogenous gonadotropin secretion.