Glutathione depletion and formation of glutathione-protein mixed disulfide following exposure of brain mitochondria to oxidative stress

Abstract

t-Butyl hydroperoxide was utilized to alter the thiol homeostasis in rat brain mitochondria. Following exposure to t-butyl hydroperoxide (50-500 μM), intramitochondrial GSH content decreased rapidly and irreversibly with a major portion of the depleted GSH being accounted for as protein-SS-Glutathione mixed disulfide. Formation of GSSG was not observed nor was efflux of GSSG or GSH from the mitochondria detected in the incubation medium. The loss of intramitochondrial GSH was accompanied by loss of protein thiols. Unlike liver mitochondria, which can reverse t-butyl hydroperoxide induced formation of GSSG, addition of 50 μM t-butyl hydroperoxide resulted in irreversible loss; indicating greater susceptibility of brain mitochondria to oxidative stress than liver mitochondria.