Caspase family genes play a critical role in the initiation and execution of 
programmed cell death. Programmed cell death is an important contributor to 
neuronal loss following cerebral ischemia. We have performed a series of 
experiments to investigate the role of a specific caspase, caspase-2, in the 
development of delayed neuronal death following transient global ischemia in the 
rat. A rat ischemic brain cDNA library was screened, and two splice-variants of 
caspase-2 mRNA were identified, caspase-2S and caspase-2L, which were highly 
homologous with the sequences of human and mouse caspase-2S and caspase-2L 
genes, respectively. RT-PCR demonstrated an increase in expression of both 
caspase-2S and caspase-2L mRNA at 8, 24 and 72 h of reperfusion after global 
ischemia. The ratio of the two PCR fragments did not change significantly 
throughout the time course of reperfusion. Western blot with monoclonal antibody 
specific to the pro-apoptotic caspase-2L splice variant revealed an increase in 
procaspase-2 (51 kDa) protein from 4 to 72 h following ischemia compared with 
sham-operated controls. Furthermore, an approximately 30-kDa cleavage product 
appeared at 8 h and increased with increasing duration of reperfusion. Thus, 
caspase-2L is both translated and activated following transient global ischemia. 
Finally, intraventricular administration of the caspase-2-like inhibitor 
(VDVAD-FMK) 30 min before induction of ischemia decreased the number of CA1 
neurons staining positively for DNA damage (Klenow-labeling assay) and increased 
the number of healthy-appearing CA1 neurons (cresyl violet) compared with 
vehicle-treated controls. Taken together, the data suggest that caspase-2 
induction and activation are important mediators of delayed neuronal death 
following transient global ischemia.