The effects of simvastatin on hippocampal caspase-3 and Bcl-2 expression following kainate-induced seizures in rats

Abstract

Status epilepticus (SE) causes neuronal loss and apoptosis by inducing several apoptosis-regulatory genes. Two such genes, cysteinyl aspartate-specific protease-3 (caspase-3), an apoptosis activator, and B-cell leukemia-2 (Bcl-2), an apoptosis suppressor, are tightly regulated for their expression and activation. Statins, inhibitors of HMG-CoA reductase, have been recently recognized as neuroprotective drugs. However, their underlying mechanisms are still unclear. In this study, we examined the neuroprotective effects of simvastatin in a rat model of SE induced by kainic acid (KA). Feeding of simvastatin for 3 days after kainate injection rescued SE-induced neuronal apoptosis, as determined by histological examination of brain sections at the level of the dorsal hippocampus. Semi-quantitative RT-PCR showed that SE treatment markedly increased caspase-3 mRNA expression and reduced Bcl-2 mRNA expression in the hippocampus. Similarly, western blot analysis and immunohistochemical analysis of the rat hippocampus demonstrated that under SE treatment, caspase-3 protein levels significantly increased and peaked at 72 h, whereas Bcl-2 protein levels decreased from 6-24 h following SE. Interestingly, simvastatin could reverse the aforementioned SE-induced changes, suggesting that the neuroprotective effects of simvastatin against neuronal apoptosis may be achieved by inhibiting caspase-3 expression and increasing Bcl-2 expression.