Activation of Caspase-3 in Neuronal Apoptosis After Focal Cerebral Ischemia in Rats

Aim:To observe the role of caspase-3 activation in neuronal apoptosis after middle cerebral artery occlusion in rats. Methods: By using the model of focal cerebral ischemia in Wistar rats, DNA fragmentation,caspase-3 mRNA and enzy- matic activity were measured in the sham-operated group and 2, 6, 18, 24, 48h reperfusion after 2h cerebral ischemia. Results: DNA fragmentation was observed in samples from injuried brain area beginning from 6~18h after and continuing for at least 2d by TUNEL and FCM. Caspase-3 mRNA levels, estimated by semiquantitative RT-PCR, were elevated three-fold by 6h and five-fold by 24 h after reperfusion. Increased caspase-3 enzymatic activity was found in cytosolic extract from ischemic area,but to a lesser extent than caspase-3 mRNA. The changes of caspase-3 enzymatic activity is consistent with DNA frag- mentation. Conclusion: It is suggested that activation of caspase-3 contributes to neuronal apoptosis after middle cerebral artery occlusion.