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Oxidative Stress, Mitochondrial Function, and Acute Glutamate Excitotoxicity in Cultured Cerebellar Granule Cells
Author(s) -
Castilho Roger F.,
Ward Manus W.,
Nicholls David G.
Publication year - 1999
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.1471-4159.1999.721394.x
Subject(s) - oligomycin , glutamate receptor , superoxide , mitochondrion , microbiology and biotechnology , excitotoxicity , reactive oxygen species , mitochondrial permeability transition pore , oxidative stress , biochemistry , biology , chemistry , programmed cell death , biophysics , apoptosis , atpase , receptor , enzyme
On exposure to glutamate, cultured rat cerebellar granule cells undergo a delayed Ca 2+ deregulation (DCD), which precedes and predicts cell death. We have previously shown that mitochondria control the sensitivity of the neurons to DCD. Mitochondrial depolarization by rotenone/oligomycin before glutamate addition is strongly neuroprotective, and the indication is therefore that mitochondrial Ca 2+ loading leads to a delayed loss of bioenergetic function culminating in DCD and cell death. In this report it is shown that superoxide (O 2 [UNK] ) generation in intact cells, monitored by oxidation of hydroethidine to ethidium, was enhanced by glutamate only when mitochondria were polarized. Production of superoxide was higher in the subset of cells undergoing DCD. In the presence of rotenone and oligomycin, addition of glutamate did not result in increased superoxide generation. Menadione‐generated superoxide enhances the DCD of cells exposed to glutamate; in contrast, glutamate‐induced DCD was potently inhibited by the presence of the cell‐permeant antioxidant manganese(III) tetrakis(4‐benzoic acid) porphyrin. An inverse correlation is observed between the cytoplasmic free Ca 2+ maintained in individual cells in the presence of glutamate and the ability of these cells to restore basal Ca 2+ when NMDA receptors are inhibited and mitochondrial Ca 2+ is released. It is concluded that mitochondrial Ca 2+ accumulation and reactive oxygen species each contribute to DCD, probably related to damage to a process controlling Ca 2+ efflux from the cell.