Contribution of a mitochondrial pathway to excitotoxic neuronal necrosis.
It is traditionally thought that excitotoxic necrosis is a passive mechanism that does not require the activation of a cell death program. In this study, we examined the contribution of the cytochrome c-dependent mitochondrial death pathway to excitotoxic neuronal necrosis, induced by exposing cultured cortical neurons to 1 mM glutamate for 6 hr and blocked by the NMDA antagonist, dizocilpine. Glutamate treatment induced early cytochrome c release, followed by activation of caspase-9 and caspase-3. Preincubation with the caspase-9 inhibitor z-LEHD-fmk, the caspase-3 inhibitor z-DEVD-fmk, or the specific pan-caspase inhibitor Q-VD-oph decreased the percentage of propidium iodide-positive neurons (52.5% +/- 3.1%, 39.4% +/- 3.5%, 44.6% +/- 3%, respectively, vs. 65% +/- 3% in glutamate + vehicle). EM studies showed mitochondrial release of cytochrome c in neurons in the early stages of necrosis and cleaved caspase-3 immunoreactivity in morphologically necrotic neurons. These results suggest that an active mechanism contributes to the demise of a subpopulation of excitotoxic necrotic neurons.
Seo
Dae-Won
DW
Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
Lopez-Meraz
Maria-Leonor
ML
Allen
Suni
S
Wasterlain
Claude Guy
CG
Niquet
Jerome
J
D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D045304:Cytochromes c / Q000187:drug effects* / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism / Q000633:toxicity; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009336:Necrosis / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009498:Neurotoxins / Q000378:metabolism / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D009498:Neurotoxins; D018698:Glutamic Acid; D045304:Cytochromes c; D053148:Caspase 3