Oxidative stress response of rat testis to model prooxidants in vitro and its modulation

Understanding the effects of prooxidants on mammalian testis either in vitro or in vivo is important, since recent evidence shows that oxidative stress can play a vital role in the etiology of male infertility. In this investigation, we have examined the oxidative stress response of adult rat testis in vitro as induced by model prooxidants (tert-butyl hydroperoxide (t-bHP) and cumene hydroperoxide (cHP) deploying two models-testicular cell suspensions (TCS) and testicular explants (TE). Significant induction of oxidative stress was observed in both models as evidenced by increased thiobarbituric acid reactive substances (TBARS) levels on incubation with hydroperoxides. The response was both concentration and time dependent. At the highest concentration (200 microM), both hydroperoxides induced a 100% increase in the TE model, compared with a dramatic (380-560%) increase in the TCS model during a 30-min incubation. Further evidence of oxidative stress such as reduction in the GSH levels and alterations in the activity of antioxidant enzymes (catalase and glutathione peroxidase) were also obtained in the TE model. In the TE model, radical scavengers, namely thiourea, urea and mannitol, as well as antioxidants such as glutathione and catalase inhibited the t-bHP-induced lipid peroxidation response to varying degree. A similar degree of protection was also evident with known antioxidants such as ascorbic acid, butylated hydroxyanisole and butylated hydroxytoluene in the TE model. Further co-incubation of TE either with mercaptosuccinate (a potent glutathione peroxidase inhibitor) or 3-aminotriazole (an irreversible catalase inhibitor) resulted in a marked increase in t-bHP-induced lipid peroxidation, clearly suggesting the importance of both of these enzymic antioxidants in rat testis in vitro. These data suggest that the TE model may be further utilized to screen antioxidants in vitro and also investigate the prooxidant potency of xenobiotics in testicular cells.