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Effects of Oxidants and Glutamate Receptor Activation on Mitochondrial Membrane Potential in Rat Forebrain Neurons
Author(s) -
Scanlon Joelle M.,
Reynolds Ian J.
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.71062392.x
Subject(s) - glutamate receptor , chemistry , biophysics , superoxide , mitochondrial permeability transition pore , membrane potential , mitochondrion , depolarization , reactive oxygen species , oxidative stress , kainate receptor , xanthine oxidase , biochemistry , microbiology and biotechnology , biology , receptor , ampa receptor , programmed cell death , apoptosis , enzyme
Both glutamate and reactive oxygen species have been implicated in excitotoxic neuronal injury, and mitochondria may play a key role in the mediation of this process. In this study, we examined whether glutamate‐receptor stimulation and oxidative stress interact to affect the mitochondrial membrane potential (ΔΨ). We measured ΔΨ in rat forebrain neurons with the ratiometric fluorescent dye JC‐1 by using laser scanning confocal imaging. Intracellular oxidant levels were measured by using the oxidation‐sensitive dyes 2′,7′‐dichlorodihydrofluorescein (DCFH 2 ) and dihydroethidium (DHE). Application of hydrogen peroxide (0.3–3 m M ) or 1 m M xanthine/0.06 U/ml xanthine oxidase decreased ΔΨ in a way that was independent of the presence of extracellular Ca 2+ and was not affected by the addition of cyclosporin A, suggesting the presence of either a cyclosporin A‐insensitive form of permeability transition, or a separate mechanism. tert ‐Butylhydroperoxide (730 µ M ) had less of an effect on ΔΨ than hydrogen peroxide despite similar effects on intracellular DCFH 2 or DHE oxidation. Hydrogen peroxide‐, tert ‐butylhydroperoxide‐, and superoxide‐enhanced glutamate, but not kainate, induced decreases in ΔΨ. The combined effect of peroxide or superoxide plus glutamate was Ca 2+ dependent and was partially inhibited by cyclosporin A. These results suggest that oxidants and glutamate depolarize mitochondria by different mechanisms, and that oxidative stress may enhance glutamate‐mediated mitochondrial depolarization.