Activation of caspase-3 in permanent and transient brain ischaemia in man

Animal studies have shown brain ischaemia to cause oxidative damage to DNA and activation of caspase-3, leading to apoptosis. These changes may be exacerbated by reperfusion. To assess caspase-3 activation after transient and permanent brain ischaemia in man, we examined brain tissue from patients who had experienced a cardiac arrest with resuscitation or an atherothrombotic brain infarct, and died 12 h to 9 days later. Sections were immunostained for activated caspase-3 or the 89 kDa caspase-3-mediated cleavage product of poly(ADP-ribose) polymerase. Brain ischaemia caused activation of caspase-3 in macrophages/microglia. Some neurons showed delayed activation of caspase-3 after cardiac arrest, but very few in atherothrombotic infarcts. In man, activation of caspase-3 plays little part in neuronal death in atherothrombotic infarcts but may contribute to delayed death of neurons after cardiac arrest.