Glutamate induces H2O2 synthesis in nonsynaptic brain mitochondria

Abstract Mitochondrial reactive oxygen species regulate many important biological processes. We studied H 2 O 2 formation by nonsynaptic brain mitochondria in response to the addition of low concentrations of glutamate, an excitatory neurotransmitter. We demonstrated that glutamate at concentrations from 10 to 50 μM stimulated the H 2 O 2 generation in mitochondria up to 4-fold, in a dose-dependent manner. The effect of glutamate was observed only in the presence of Ca 2+ (20 μM) in the incubation medium, and the rate of calcium uptake by the brain mitochondria was increased by up to 50% by glutamate. Glutamate-dependent effects were sensitive to the NMDA receptor inhibitors MK-801 (10 μM) and D-AP5 (20 μM) and the inhibitory neurotransmitter glycine (5 mM). We have shown that the H 2 O 2 formation caused by glutamate is associated with complex II and is dependent on the mitochondrial potential. We have found that nonsynaptic brain mitochondria are a target of direct glutamate signaling, which can specifically activate H 2 O 2 formation through mitochondrial respiratory chain complex II. The H 2 O 2 formation induced by glutamate can be blocked by glycine, an inhibitory neurotransmitter that prevents the deleterious effects of glutamate in brain mitochondria.