PT - JOURNAL ARTICLE AU - C. Marc Luetjens AU - Nguyen Truc Bui AU - Bernd Sengpiel AU - Gudrun Münstermann AU - Monika Poppe AU - Aaron J. Krohn AU - Elke Bauerbach AU - Josef Krieglstein AU - Jochen H. M. Prehn TI - Delayed Mitochondrial Dysfunction in Excitotoxic Neuron Death: Cytochrome <em>c</em> Release and a Secondary Increase in Superoxide Production AID - 10.1523/JNEUROSCI.20-15-05715.2000 DP - 2000 Aug 01 TA - The Journal of Neuroscience PG - 5715--5723 VI - 20 IP - 15 4099 - http://www.jneurosci.org/content/20/15/5715.short 4100 - http://www.jneurosci.org/content/20/15/5715.full SO - J. Neurosci.2000 Aug 01; 20 AB - An increased production of superoxide has been shown to mediate glutamate-induced neuron death. We monitored intracellular superoxide production of hippocampal neurons during and after exposure to the glutamate receptor agonist NMDA (300 μm). During a 30 min NMDA exposure, intracellular superoxide production increased significantly and remained elevated for several hours after wash-out of NMDA. After a 5 min exposure, superoxide production remained elevated for 10 min, but then rapidly returned to baseline. Mitochondrial membrane potential also recovered after wash-out of NMDA. However, recovery of mitochondria was transient and followed by delayed mitochondrial depolarization, loss of cytochrome c, and a secondary rise in superoxide production 4–8 hr after NMDA exposure. Treatment with a superoxide dismutase mimetic before the secondary rise conferred the same protection against cell death as a treatment before the first. The secondary rise could be inhibited by the complex I inhibitor rotenone (in combination with oligomycin) and mimicked by the complex III inhibitor antimycin A. To investigate the relationship between cytochrome c release and superoxide production, human D283 medulloblastoma cells deficient in mitochondrial respiration (ρ− cells) were exposed to the apoptosis-inducing agent staurosporine. Treatment with staurosporine induced mitochondrial release of cytochrome c, caspase activation, and cell death in control and ρ− cells. However, a delayed increase in superoxide production was only observed in control cells. Our data suggest that the delayed superoxide production in excitotoxicity and apoptosis occurs secondary to a defect in mitochondrial electron transport and that mitochondrial cytochromec release occurs upstream of this defect.