RESUMEN
In glial cells, glutamate exposure causes alterations in cell redox status, mainly mediated by glutathione depletion and reactive oxygen species generation. These effects finally lead to astrocyte dysfunction which contributes to the pathogenesis of several neurological disorders. This study was aimed to investigate the involvement of the NF-kappaB pathway in oxidative stress induced by glutamate exposure in primary cultures of astrocytes. Further, we evaluated the power of the antioxidants genistein (0.1-10 microM) and IRFI 016 (20-80 microM), a synthetic tocopherol analogue, compared with glutathione ethyl ester (10-50 microM) and cysteamine-HCl (100-500 microM), to antagonize the effects elicited by glutamate (500 microM). Alterations of cell redox status were reduced, in a dose-dependent way, by antioxidants; in particular, 80 microM IRFI 016 and 10 microM genistein almost completely restored glutathione basal levels and significantly diminished ROS production, as well as 100 microM glutathione ethyl ester. These antioxidant effects were stronger than those caused by 500 microM cysteamine-HCl. Further, glutamate promoted the up-regulation of p50 and p65 NF-kappaB subunits and their nuclear translocation, as revealed by Western blot analysis and electrophoretic mobility shift assay of both subunits. The activation of p50 and p65 NF-kappaB subunits induced by glutamate exposure was significantly reduced by IRFI 016, acting in a dose-dependent manner. Altogether, these data confirm that the NF-kappaB pathway is involved in cell response to oxidative stress induced by glutamate injury in primary astrocyte cultures, and suggest that the use of antioxidants, such as IRFI 016, may be a helpful pharmacological strategy for neuroprotection.