ACTIVATION OF CPP-32 PROTEASE IN HIPPOCAMPAL-NEURONS FOLLOWING ISCHEMIA AND EPILEPSY

Recent in vitro studies indicate an involvement of members of the inte rleukin-IP converting enzyme (ICE) family of proteases in programmed n euronal cell death. Cell death of hippocampal neurons in animal models of cerebral ischemia and epilepsy shows morphological features of apo ptosis and can be prevented by administration of protein synthesis inh ibitors suggesting that de novo synthesis of components of the cell de ath program is necessary for neuronal apoptosis. In the present study we demonstrate by in situ hybridization analysis that expression of CP P-32, an ICE-related protease, is significantly upregulated in CA1 hip pocampal neurons following global ischemia induced by cardiac arrest a nd in hippocampal neurons of the CA3/CA4 region after kainate-mediated epilepsy, respectively. Moreover, an increase in CPP-32-like proteoly tic activity was detected in hippocampal extracts 24 h after ischemia using the fluorogenic CPP-32 substrate Ac-DEVD-AMC. Activation of CPP- 32 clearly preceded cell death of hippocampal neurons as assessed by i n situ end-labelling of nuclear DNA fragments. These results indicate that CPP-32 protease may be activated at both the transcriptional and post-translational level during neuronal apoptosis and that activation correlates with the selective vulnerability of hippocampal pyramidal neurons to ischemic and epileptic insults. (C) 1997 Elsevier Science B .V.