Intracerebral hemorrhage-induced neuronal death.
OBJECTIVE
The mechanisms underlying neural injury in intracerebral hemorrhage (ICH) remain uncertain. The present two-part study investigated cell death in the region of ICH and its association with caspase-3 activation.


METHODS
ICH was produced in adult rats by injection of 100 microl of autologous blood or saline into the right basal ganglia. The animals' brains were removed at 6 hours or at 1, 3, 7, or 14 days after hemorrhage. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin in situ nick end-labeling (TUNEL) was used to detect deoxyribonucleic acid (DNA) fragmentation. TUNEL-positive cells were quantified. Caspase-3 activation was measured by Western blotting and immunohistochemistry. Double labeling was used to compare TUNEL with caspase-3 distribution and to identify the cell types affected. TUNEL-positive cells were also quantified at 6 hours, 1 day, and 3 days after injection of 5 U of thrombin into the right basal ganglion.


RESULTS
At 6 hours, TUNEL-positive cells appeared in the ICH model (but not in the saline control brains) and were present for more than 2 weeks after ICH, peaking at 3 days. Western blot analysis revealed that the increase in immunoreactivity for the activated caspase-3 precedes that of DNA fragmentation, peaking at 1 day after ICH and declining thereafter. Immunohistochemistry analysis showed nucleus translocation of caspase-3 after ICH. Double-labeling studies demonstrated that both neurons and astrocytes surrounding the clot were TUNEL-positive. In addition, TUNEL and caspase-3 were colocalized in the same cells. Intracerebral thrombin injection elicited DNA fragmentation similar to that observed after the injection of blood.


CONCLUSIONS
Double-strand breaks in genomic DNA and induction of caspase-3 were demonstrated adjacent to parenchymal hematoma in the animals' brains. These results provide evidence that cell loss after ICH is associated with activation of caspase-3.
Gong
C
C
Department of Surgery, University of Michigan, Ann Arbor 48109-0532, USA. chaog@umich.edu
Boulis
N
N
Qian
J
J
Turner
D E
DE
Hoff
J T
JT
Keep
R F
RF
D000818:Animals; D001479:Basal Ganglia / Q000473:pathology; D020145:Basal Ganglia Hemorrhage / Q000473:pathology; D001921:Brain / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000502:physiology*; D002543:Cerebral Hemorrhage / Q000473:pathology*; D004249:DNA Damage; D004789:Enzyme Activation; D020287:In Situ Nick-End Labeling; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013917:Thrombin / Q000633:toxicity
D013917:Thrombin; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases