Effect of 1-methyl-4-phenylpyridinium on glutathione in rat pheochromocytoma PC 12 cells

We investigated the effect of the selective dopaminergic neurotoxin 1-methy l-4-phenylpyridinium (MPP+) on glutathione redox status and the generation of reactive oxygen intermediates (ROI) in rat pheochromocytoma PC 12 cells in vitro. Treatment with MPP+ (250 mu M) led to a 63% increase of reduced g lutathione (GSH) after 24 h, while a 10-fold higher concentration of MPP+ ( 2.5 mM) depleted cellular GSH to 12.5% of control levels within that time. Similarly, the complex I-inhibitor rotenone induced a time-dependent loss o f GSH at 1 and 10 mu M, whereas treatment with lower concentrations of rote none (0.1, 0.01 mu M) increased cellular GSH. Both MPP+ and rotenone increa sed cellular levels of oxidised glutathione (GSSG) and the higher concentra tions of both compounds led to an elevated ratio of oxidised glutathione (G SSG) vs total glutathione (GSH + GSSG) indicating a shift in cellular redox balance. MPP+ or rotenone did not induce the generation of ROI or signific ant elevation of intracellular levels of thiobabituric acid reactive substa nces (TBARS) for up to 48 h. Our data suggest that MPP+ has differential ef fects on glutathione homeostasis depending on the degree of complex I-inhib ition and that inhibition of complex I is not sufficient to generate ROI in this paradigm. (C) 2000 Elsevier Science Ltd. All rights reserved.