Matrix metalloproteinase 9 inhibition reduces early brain injury in cortex after subarachnoid hemorrhage.

This study investigated the role of matrix metalloproteinase-9 (MMP-9) in early brain injury (EBI) after subarachnoid hemorrhage (SAH). Sprague-Dawley male rats (n=30) between 250 and 300 g were used. SAH was produced by injecting autologous arterial blood into the prechiasmatic cistern. SB-3CT, a selective MMP-9 inhibitor, was injected intraperitoneally after SAH induction. MMP-9 protein expression was measured by western blot; laminin expression and neuronal cells in the cerebral cortex were studied by immunohistochemistry and TUNEL staining at 24h after SAH. MMP-9 expression was increased after SAH and decreased by SB-3CT inhibition at 24h after SAH (P<0.01). Laminin, the substrate of MMP-9, was decreased at 24h after SAH, and SB-3CT prevented laminin degradation. The number of TUNEL-positive neurons in cerebral cortex was increased after SAH and decreased by SB-3CT (P<0.01). MMP-9 may be involved in EBI after SAH and inhibition of MMP-9 may reduce EBI in cerebral cortex.