Cell death starts early after subarachnoid hemorrhage.

Brain injury begins early after aneurysmal subarachnoid hemorrhage (SAH). Although cell death via apoptosis and necrosis is known to be present in brain 24 h after SAH, it is not known how soon after SAH cell death begins. We have previously described structural changes in rat brain microvessels 10 min after induction of SAH by endovascular puncture. This study examined brain for evidence of cell death beginning 10 min after induction of SAH. Cleaved caspase-3 (cl-caspase-3) staining was evident in vascular and parenchymal cells at 10 min after SAH and was significantly greater than in time-matched, sham-operated controls. The number of cl-caspase-3 positive cells was increased further at 24 h after SAH. TUNEL assay revealed apoptotic cells present at 10 min, with substantially more at 24 h after SAH. Scattered Fluoro-Jade positive neurons appeared at 1h after SAH and their number increased with time. At 1 h Fluoro-Jade positive neurons were present in cortical and subcortical regions but not in hippocampus; at 24h they were also present in hippocampus and were significantly greater in the hemisphere ipsilateral to the vascular puncture. No Fluoro-Jade staining was present in shams. These data demonstrate an early activation of endothelial and parenchymal cells apoptosis and neuronal necrosis after SAH and identifies endpoints that can be targeted to reduce early brain injury after SAH.