Inhibitory effects of stress-activated nitric oxide on antioxidant enzymesand testicular steroidogenesis

The messenger role of nitric oxide (NO) in immobilization stress-induced in hibition of testicular steroidogenesis has been previously suggested. In ac cord with this, here, we show that the intratesticular injection of isosorb ide dinitrate (ISDN; 2 x 2.5 mg/testis). an NO donor. mimicked the action o f stress on serum testosterone concentrations and hCG-stimulated testostero ne production in rat testicular tissue. When added in vitro. ISDN inhibited testicular 3 beta -hydroxysteroid dehydrogenase and 17 alpha -hydroxylase/ lyase. Immobilization stress and injections of ISDN also decreased the acti vity of catalase, glutathione peroxidase. glutathione transferase, and glut athione reductase in the interstitial compartment of testis. When stressed rats were treated concomitantly with bilateral intratesticular injections o f N-omega-nitro-L-arginine methyl ester, a non-selective NOS inhibitor (2 x 600 mug/testis). the activities of antioxidative enzymes, as well as serum testosterone concentration, were partially normalized. These results indic ate that stress-induced stimulation of the testicular NO signalling pathway leads to inhibition of both steroidogenic and antioxidant enzymes. (C) 200 1 Elsevier Science Ltd. All rights reserved.