Antioxidant enzymatic system in neuronal and glial cells enriched fractions of rat brain after aluminum exposure.

The aim of this work was to investigate as to how neurons and glial cells separated from the brain cortex respond to oxidative stress induced by aluminum. Female SD rats were exposed to aluminum at the dose level of 100 mg/kg b.w. for 8 weeks. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex by sieving the trypsinated homogenate through a series of nylon meshes, followed by centrifugation on ficoll density gradient. Total glutathione content, glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-s-transferase (GST) along with antioxidant enzymes superoxide dismutase (SOD), catalase were estimated in neuronal and glial-enriched fractions in both control (N-c and G-c) and aluminum exposed animals (N-a and G-a). Secondary products of lipid peroxidation that is MDA levels were estimated by measuring the (TBARS) levels. Our results indicate that TBARS levels were significantly higher in glial cell fraction of unexposed controls (Gc) than the neuronal cells (Nc). Correspondingly the glial cells had higher levels of GSH, GSSG, GPx and GST where as neurons had higher levels of catalase, SOD and GR. Following aluminum exposures significant increase in the TBARS levels was observed in neurons as compared to glial cells which also showed a significant decrease in SOD and catalase activity. The decrease in the TBARS levels in the glial cells could be related to the increase in the GSH levels, GR activity, and GST activity which were found to be increased in glial enriched fractions following aluminum exposure. The increase in activity of various enzymes viz GR, GST in glial cells as compared to neurons suggests that glial cells are actively involved in glutathione homeostasis. Our conclusion is that glial and neurons isolated from rat cerebral cortex show a varied pattern of important antioxidant enzymes and glial cells are more capable of handling the oxidative stress conditions.