Figure 2 Caspase and Calpain activity in the rostral hippocampus after transient forebrain ischemia. Representative photomicrographs illustrating pathological protease activity in the rostral hippocampus at 30 minutes (A & B) and 48 hours (C & D) after 10 minutes of transient forebrain ischemia (TFI). Boxes in the low magnification images represent the source of high magnification images shown below. At 30 minutes after TFI, rostral dentate gyrus granule neurons immunolabel for caspase-cleaved α-spectrin (Ab246, 1:2000). At 48 hours after TFI, CA1 sector pyramidal neurons immunolabel for calpain-cleaved α-spectrin (Ab38, 1:30:000). These results suggest that rapidly triggered post-ischemic caspase activation causes early apoptosis in the rostral dentate gyrus, while delayed post-ischemic calpain activation causes delayed necrosis of CA1 sector pyramidal neurons.