THE INVOLVEMENT OF NITRIC-OXIDE IN STRESS-IMPAIRED TESTICULAR STEROIDOGENESIS

The participation of the nitric oxide (NO) pathway in downregulation o f testicular steroidogenesis in normal and stressed rats was investiga ted both in vivo and in vitro. In Leydig cells from normal animals, is osorbide dinitrate, an NO donor, decreased the human chorionic gonadot ropin (CG)-stimulated and progesterone-derived androgen production. Al so, the intratesticular injection of a precursor of NO, arginine(10 mg /testis), transiently decreased serum androgen levels and inhibited hu man CG-stimulated androgen production in acute testicular cultures. Th ese effects were eliminated in rats cotreated with N-omega-nitro-L-arg inine methyl eater (L-NAME) (2 X 600 mu g/each testis). Acute immobili zation stress (2 h) decreased serum androgen levels and inhibited huma n CG-stimulated androgen production in vitro. These effects were accom panied by a significant increase in nitrite, a stable oxidation produc t of NO, in testicular cultures. Bilateral intratesticular injection o f L-NAME prevented the stress-induced decrease of human CG-stimulated androgen production, and significantly reduced the nitrite levels. The se results implicate NO in normal and stress-impaired testicular stero idogenesis. (C) 1998 Elsevier Science B.V.