Involvement of caspase-3-like protease in the mechanism of cell death following focally evoked limbic seizures.
The cysteine protease caspase-3 may be involved in the mechanism of cell death following seizures. Using a rat model of focally evoked limbic epilepsy with continuous electroencephalography monitoring, we investigated seizure-induced changes in caspase-3 protein expression and processing, enzyme activity, and the in vivo effect of caspase-3 inhibition. Seizures were induced by intraamygdaloid injection of kainic acid (0.1 microg) and were terminated after 45 min by diazepam (30 mg/kg) administration. Animals were killed 0-72 h following diazepam administration. Levels of the 32-kDa proenzyme form of caspase-3 were unaffected by seizures. Levels of the 17-kDa cleaved (active) fragment of caspase-3 were almost undetectable in control brain, but were increased significantly at 4 and 24 h within ipsilateral hippocampus and cortex in seizure animals. Caspase-3-like protease activity was increased within the ipsilateral hippocampus at 8 and 24 h following seizures. Caspase-3 immunoreactivity was increased within the vulnerable ipsilateral CA3/CA4 subfield at 24 and 72 h following seizures and was associated predominantly, but not exclusively, with neurons exhibiting DNA fragmentation. The putatively selective caspase-3 inhibitor N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone significantly improved neuronal survival bilaterally within the hippocampal CA3/CA4 subfields following seizures. Collectively, these data suggest that caspase-3 may play a significant role in the mechanism by which neurons die following seizures.
Henshall
D C
DC
Department of Neurology, University of Pittsburgh, Pennsylvania, USA.
Chen
J
J
Simon
R P
RP
D000818:Animals; D001921:Brain / Q000201:enzymology; D053148:Caspase 3; D020169:Caspases / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004569:Electroencephalography; D008032:Limbic System / Q000503:physiopathology*; D008297:Male; D018696:Neuroprotective Agents / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D014018:Tissue Distribution
D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D018696:Neuroprotective Agents; D009842:Oligopeptides; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases