H2O2 at physiological concentrations modulates Leydig cell function inducing oxidative stress and apoptosis

H2O2 is one of the active reactive oxygen species secreted by macrophages that are seen closely aligned with Leydig cells in the testicular interstitium. The present study was initiated to investigate the role of H2O2 on Leydig cell function in vitro at physiological concentrations. Significant decrease in both testosterone production (p < 0.05) and 3 beta-hydroxysteroid dehydrogenase activity (p < 0.05) in adult Leydig cells were observed even with H2O2 at low concentrations (30 - 50 mu M). H2O2 exposure increased oxidative stress in Leydig cells with the rise in lipid peroxidation and fall in the activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT) & glutathione-s-transferase (GST). There was also a marginal increase (similar to 8%) in cell apoptosis accompanied by rise in FasL expression and caspase-3 activation. The above findings indicate that H2O2 as a bio-molecule modulates Leydig cell function at or below physiological concentrations through a variety of actions like decrease in steroidogenic enzyme activity and increase in oxidative stress and apoptosis.