GLUTAMATE TOXICITY ON A PC12 CELL-LINE INVOLVES GLUTATHIONE (GSH) DEPLETION AND OXIDATIVE STRESS

The effect of antioxidants and reducing agents on glutamate-induced cy totoxicity was examined using PC12 cells. The antioxidants vitamin E, idebenone, and selegiline protected cells against the cytotoxicity obs erved 24 h after exposure to 0.5 or 10 mM glutamate, as determined by lactate dehydrogenase leakage, even when added 3 h after glutamate. Th e reducing agents, glutathione (GSH) anti dithiothreitol (DTT), also p rovided protection against the cytotoxicity of glutamate. Preincubatio n of PC12 cells with the antioxidants mentioned above, or the incubati on with those antioxidants after exposure to glutamate for 3 h, preven ted the reduction of viability caused by glutamate. Cystine uptake was inhibited by exposure of cells to glutamate, as determined by L-[S-35 ]-cystine uptake. Incubation of cells with 0.5 or 10 mM glutamate caus ed a marked decrease in cellular GSH levels, not prevented by antioxid ants, The activity of GSSG reductase was decreased by glutamate and th is inhibition was reverted in the presence of the reducing agents GSH and DTT. These results indicate that glutamate toxicity on PC12 cells results from the inhibition of cystine uptake with consequent GSH depl etion and oxidative stress, suggesting that antioxidants may reduce th e cellular damage in pathologic conditions associated with excessive g lutamate release. (C) 1997 Elsevier Science Inc.