Post-ischemic activation of caspase-3 in the rat hippocampus: evidence of an axonal and dendritic localisation.
The relationship between caspase-3 activation and delayed neuronal death after ischemia was examined. Expression of caspase-3 was evaluated by colorimetric assay, immunoblotting and by immunohistochemistry. Apoptosis was characterised by terminal desoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labelling. Immunohistochemistry showed caspase-3 activation in the whole hippocampus as early as 30 min after ischemia with exclusive localisation in fiber systems, especially in the perforant path and mossy fibers, Schaffer-collaterals, as well as apical and basal dendrites of pyramidal cells. One day post-ischemia, the 18 kDa cleavage product of caspase-3 (p18) was seen in all cell compartments (nucleus, cytosol and dendrites) throughout the entire subfields and the dentate gyrus with high distribution in mossy fibers. Two days post-ischemia, p18 kDa was only seen in the nuclei and cytosol of hippocampal cells without specific regional differences among hippocampal subfields. A significant number of apoptotic cells appeared only in the CA1 pyramidal cells at 2-3 days post-ischemia. Our data provides the first evidence that caspase-3 activation was detectable in the trisynaptic pathway fiber bundles which probably correspond to perforant path, alvear path and collaterals of Schaffer, and that activation of caspase-3 led to execution of apoptotic cell death program in selectively vulnerable areas, but not in the resistant area of the hippocampus.
Rami
A
A
Institute of Anatomy III, Dr. Senckenbergische Anatomie, Faculty of Medicine, Clinic of the Johann-Wolfgang-Goethe-University, Theodor-Ster-Kai 7, 60590 Frankfurt/Main, Germany. rami@em.uni-frankfurt.de
Jansen
S
S
Giesser
I
I
Winckler
J
J
D000818:Animals; D001369:Axons / Q000201:enzymology*; D015153:Blotting, Western; D002545:Brain Ischemia / Q000201:enzymology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D003124:Colorimetry; D003712:Dendrites / Q000201:enzymology*; D004789:Enzyme Activation; D006624:Hippocampus / Q000187:drug effects* / Q000201:enzymology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D051381:Rats; D017208:Rats, Wistar
C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases