Caspase-3-associated apoptotic cell death in excitotoxic necrosis of the entorhinal cortex following intraperitoneal injection of kainic acid in the rat.
The present study is directed to study: (a) bax translocation and cytochrome c release as mediators of the mitochondrial pathway of apoptosis; (b) Fas-L (Fas-ligand) expression as an indicator of the possible involvement of the Fas/Fas-L signaling pathway; and (c) active caspase-3 expression as the main executioner of caspase-mediated apoptosis, in rats receiving an intraperitoneal injection of the glutamate analogue kainic acid (KA) at a dose of 9 mg/kg, which is sufficient to produce generalized seizures and excitotoxic cell death in the entorhinal cortex. Sub-fractionation studies of entorhinal cortex homogenates have shown cytochrome c and cytochrome oxidase IV localized in the mitochondrial fraction, and Bax localized in the cytosolic fraction. No modifications in the sub-cellular distribution of cytochrome c and Bax have been observed at 6 h and 24 h in KA-treated rats. Morphological studies have shown cytoplasmic shrinkage and nuclear condensation consistent with necrosis in the entorhinal cortex. Many neurons (about 30% of dying cells) are stained with the method of in situ end-labeling of nuclear DNA fragmentation. Yet only about 5% of dying cells have apoptotic morphology. A percentage of dying cells (5% at 6 h and 40% at 24 h) over-express Fas-L but only about 2% of dying cells at 24 h post-injection express cleaved caspase-3 (17 kD). The present data further support the concept that necrosis is the predominant form of cell death in the entorhinal cortex, although caspase-3-dependent apoptotic cell death may play a limited role, in the present paradigm of KA-induced excitotoxicity.
Puig
B
B
Unitat Neuropatología, Departament Biologia Cel.lular i Anatomia Patològica, Universitat de Barcelona, Campus de Bellvitge, Spain.
Ferrer
I
I
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D003574:Cytochrome c Group / Q000187:drug effects / Q000378:metabolism; D018728:Entorhinal Cortex / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D053222:Fas Ligand Protein; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009336:Necrosis; D009474:Neurons / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D009498:Neurotoxins / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051028:bcl-2-Associated X Protein
C494828:Bax protein, rat; D003574:Cytochrome c Group; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D009498:Neurotoxins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D018698:Glutamic Acid; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D007608:Kainic Acid