Ischemia leads to apoptosis--and necrosis-like neuron death in the ischemic rat hippocampus.
Morphological evidence of apoptosis in transient forebrain ischemia is controversial. We therefore investigated the time sequence of apoptosis-related antigens by immunohistochemistry and correlated it with emerging nuclear patterns of cell death in a model of transient forebrain ischemia in CA1 pyramidal cells of the rat hippocampus. The earliest ischemic changes were found on day 2 and 3, reflected by an upregulation of phospho-c-Jun in a proportion of morphologically intact CA1 neurons, which matched the number of neurons that succumbed to ischemia at later time points. At day 3 and later 3 ischemic cell death morphologies became apparent: pyknosis, apoptosis-like cell death and necrosis-like cell death, which were confirmed by electron microscopy. Activated caspase-3 was present in the vast majority of cells with apoptosis-like morphology as well as in a small subset of cells undergoing necrosis; its expression peaked on days 3 to 4. Silver staining for nucleoli, which are a substrate for caspase-3, revealed a profound loss of nucleoli in cells with apoptosis-like morphology, whereas cells with necrosis-like morphology showed intact nucleoli. Overall, cells with apoptosis-like morphology and/or caspase-3 expression represented a minor fraction (<10%) of ischemic neurons, while the vast majority followed a necrosis-like pathway. Our studies suggest that CA1 pyramidal cell death following transient forebrain ischemia may be initiated through c-Jun N-terminal kinase (JNK) pathway activation, which then either follows an apoptosis-like cell death pathway or leads to secondary necrosis.
Müller
Georg Johannes
GJ
Molecular Neuropathology Group, University of Copenhagen, Denmark.
Stadelmann
Christine
C
Bastholm
Lone
L
Elling
Folmer
F
Lassmann
Hans
H
Johansen
Flemming Fryd
FF
D000818:Animals; D017209:Apoptosis; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D004076:Digoxigenin / Q000378:metabolism; D053331:Ectodysplasins; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008855:Microscopy, Electron, Scanning / Q000379:methods; D009336:Necrosis / Q000473:pathology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D017966:Pyramidal Cells / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D016622:Silver Staining / Q000379:methods; D013997:Time Factors
D053331:Ectodysplasins; D005904:Glial Fibrillary Acidic Protein; D008565:Membrane Proteins; D016755:Proto-Oncogene Proteins c-jun; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D004076:Digoxigenin