Caspase-3 is not activated in seizure-induced neuronal necrosis with internucleosomal DNA cleavage.
A caspase-3-activated DNase produces internucleosomal DNA cleavage (DNA laddering). We determined whether caspase-3 is activated by lithium-pilocarpine-induced status epilepticus in six brain regions with necrosis-induced DNA laddering. The thymuses of adult rats given methamphetamine or normal saline were used as controls for apoptosis. Some 6-8 h after methamphetamine treatment, thymocytes showed apoptosis by electron-microscopic examination, positive terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), DNA laddering, cleavage of caspase-3 into its active p17 subunit, active caspase-3 immunoreactivity, and a 25-fold increase in caspase-3-like activity. Six hours after SE, necrotic neurons by electron-microscopic examination in hippocampus, amygdala and piriform, entorhinal and frontal cortices showed no TUNEL and no DNA laddering. Twenty-four hours after seizures, most necrotic neurons were negative for TUNEL, some were positive, but all regions showed DNA laddering. However, 6 and 24 h after seizures, active caspase-3 immunoreactivity was negative, caspase-3-like activity did not increase, and western blot analysis failed to show the p17 subunit. In addition, 24 h after seizures,microdialytic perfusion of carbobenzoxy-valyl-alanyl-aspartyl (O-methylester) fluoromethylketone was not neuroprotective. Thus, caspase-3 is not activated in brain regions with seizure-induced neuronal necrosis with DNA laddering. Either caspase-activated DNase is activated by another enzyme, or a caspase-independent DNase is responsible for the DNA cleavage.
D000590:Amino Acid Chloromethyl Ketones / Q000008:administration & dosage; D000818:Animals; D017209:Apoptosis; D001921:Brain / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D053938:DNA Fragmentation; D004195:Disease Models, Animal; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D020287:In Situ Nick-End Labeling; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology; D017551:Microdialysis; D009336:Necrosis; D009474:Neurons / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D010862:Pilocarpine; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D013226:Status Epilepticus / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D013950:Thymus Gland / Q000187:drug effects / Q000473:pathology; D013997:Time Factors
D000590:Amino Acid Chloromethyl Ketones; D004791:Enzyme Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D010862:Pilocarpine; D008694:Methamphetamine; D004247:DNA; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases