Contribution of nitric oxide, superoxide anion, and peroxynitrite to activation of mitochondrial apoptotic signaling in hippocampal CA3 subfield following experimental temporal lobe status epilepticus.
OBJECTIVE
One cellular consequence of status epilepticus is apoptosis in the hippocampal CA3 subfield. We evaluated the hypothesis that the repertoire of cellular events that underlie such elicited cell death entails mitochondrial dysfunction induced by an excessive production of nitric oxide synthase II (NOS II)-derived NO, increased superoxide anion (O(2)(-)) production, and peroxynitrite formation.


METHODS
In Sprague-Dawley rats, kainic acid was microinjected unilaterally into the hippocampal CA3 subfield to induce bilateral seizure-like electroencephalography (EEG) activity. The effects of pretreatments with various test agents on the induced O(2)(-) production, peroxynitrite formation, mitochondrial respiratory chain enzyme activities, cytochrome c/caspase-3 signaling, and DNA fragmentation in bilateral CA3 subfields were examined.


RESULTS
Significantly and temporally correlated increase in O(2)(-) and peroxynitrite levels (3 to 24 h), depressed mitochondrial Complex I activity (3 h), enhanced translocation of cytochrome c to cytosol (day 1), and augmented activated caspase-3 (day 7) and DNA fragmentation (day 7) were detected bilaterally in hippocampal CA3 subfields after the elicitation of sustained seizure. Pretreatment with microinjection into the bilateral hippocampal CA3 subfield of a water-soluble formulation of coenzyme Q(10); a selective NOS II inhibitor, S-methylisothiourea; a superoxide dismutase mimetic, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl; an active peroxynitrite decomposition catalyst, 5,10, 15,20-tetrakis-(N-methyl-4-pyridyl)- porphyrinato iron (III); or a peroxynitrite scavenger, L-cysteine significantly blunted these cellular events.


CONCLUSIONS
Prolonged seizures prompted NO-, O(2)(-)-, and peroxynitrite-dependent reduction in mitochondrial respiratory enzyme Complex I activity, leading to cytochrome c/caspase-3-dependent apoptotic cell death in the hippocampal CA3 subfield after induction of experimental temporal lobe status epilepticus.
Chuang
Yao-Chung
YC
Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Taiwan, Republic of China.
Chen
Shang-Der
SD
Liou
Chia-Wei
CW
Lin
Tsu-Kung
TK
Chang
Wen-Neng
WN
Chan
Samuel H H
SH
Chang
Alice Y W
AY
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism; D053938:DNA Fragmentation; D004195:Disease Models, Animal; D004569:Electroencephalography; D014450:Electron Transport Complex III / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004833:Epilepsy, Temporal Lobe / Q000139:chemically induced / Q000473:pathology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure*; D007608:Kainic Acid; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013481:Superoxides / Q000378:metabolism*; D013997:Time Factors; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology
D004791:Enzyme Inhibitors; D009243:NAD; D013481:Superoxides; D014451:Ubiquinone; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D053148:Caspase 3; D010751:Phosphopyruvate Hydratase; D014450:Electron Transport Complex III; C024989:coenzyme Q10; D007608:Kainic Acid