ABSTRACT: Depletion of glutathione has been shown to occur in autopsied brains of patients with Parkinson's disease (PD) and in animal models of PD. The goal of this study was to determine whether chronic glutathione (GSH) deficiency per se resulted in complex I inhibition and/or dopamine depletion and whether these indices were further potentiated by aging or administration of paraquat, a redox-cycling herbicide that produces a PD-like neurodegeneration model in rodents (Brooks, A. I., Chadwick, C. A., Gelbard, H. A., Cory-Slechta, D. A., and Federoff, H. J. [1999]. Paraquat elicited neurobehavioral syndrome caused by dopaminergic neuron loss. Brain Res. 823, 1-10; McCormack, A. L., Thiruchelvam, M., Manning-Bog, A. B., Thiffault, C., Langston, J. W., Cory-Slechta, D. A., and Di Monte, D. A. [2002]