Caspase-3-dependent and -independent apoptosis in focal brain ischemia.
BACKGROUND
Although extensive caspase-3 activation has been demonstrated in experimental brain ischemia produced in neonatal rat, the role this caspase plays in the focal ischemia of adult brain is not clear, as the levels of caspase-3 in adult rat brain are extremely low. This raises the question whether caspase-3 synthesis and activation are essential for execution of the apoptotic program and DNA fragmentation in permanent brain ischemia, a condition that impairs cellular protein synthesis.


METHODS
Rat middle cerebral artery was permanently occluded and histochemical detection of procaspase-3, active caspase-3 and DFF 40/CAD and apoptotic morphology analysis were performed at 6, 24, 48, and 72 hours after occlusion.


RESULTS
Necrosis and two types of programmed cell death (PCD) are identified in this study of permanent focal brain ischemia. The first type of PCD is represented by active caspase-3 and DFF 40/CAD-positive cells. The second type of PCD is represented by caspase-3 and DFF40/CAD negative cells, which display morphological signs of apoptosis-like PCD: namely, nuclear chromatin condensation in lump masses and apoptotic body formation. The cells of the first type have a maximum number noted after 24 hours of ischemia. The cells of the second type are primarily seen after 48 and 72 hours of ischemia. Necrotic cells, which are also detected in the stroke, are caspase-3 negative, and have swollen nuclei, without chromatin condensation and apoptotic body formation.


CONCLUSIONS
Our results indicate that in permanent brain ischemia in adult rats, PCD processes occur differently in various parts of ischemic zone. In conditions of severe energy depletion, the reactions of cellular disassembly and packaging into apoptotic bodies are accomplished without either caspase-3 expression or the activation of caspase-3-dependent deoxyribonuclease.
Didenko
Vladimir V
VV
Department of Neurosurgery and Surgical Service, Baylor College of Medicine and VAMC, Houston, Texas 77030, USA.
Ngo
Hop
H
Minchew
Candace L
CL
Boudreaux
Denise J
DJ
Widmayer
Marsha A
MA
Baskin
David S
DS
D000818:Animals; D017209:Apoptosis; D001221:Aspartate Carbamoyltransferase / Q000378:metabolism; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism; D004080:Dihydroorotase / Q000378:metabolism; D004792:Enzyme Precursors / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000201:enzymology* / Q000473:pathology; D008297:Male; D020768:Middle Cerebral Artery; D009097:Multienzyme Complexes / Q000378:metabolism; D009336:Necrosis; D009474:Neurons / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D000075223:Poly-ADP-Ribose Binding Proteins; D051381:Rats; D020318:Rats, Long-Evans; D013997:Time Factors
C033626:CAD trifunctional enzyme; D004792:Enzyme Precursors; D009097:Multienzyme Complexes; D000075223:Poly-ADP-Ribose Binding Proteins; D001221:Aspartate Carbamoyltransferase; D003851:Deoxyribonucleases; C491882:Dffb protein, rat; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D004080:Dihydroorotase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)