Neuroprotective Capabilities of Tanshinone IIA against Cerebral Ischemia/Reperfusion Injury via Anti-apoptotic Pathway in Rats

Danshen, derived from the dried root or rhizome of Salviae miltiorrhizae BGE., has Tanshinone IIA (TSA) as one of its active ingredients. Recent reports have shown that TSA can inhibit the apoptosis induced by serum withdrawal or ethanol in cultured PC12 cells. However, whether TSA has any neuroprotective effect remains unknown. In this study, we investigated the effects of TSA on cerebral apoptosis induced by middle cerebral artery occlusion (MCAO) in which cerebral ischemia had been induced 2h earlier. Twenty-four hours after reperfusion, the rats were assessed for infarct volume etc. Intraperitoneal administration of 25 and 40 mg/kg TSA 10min after MCAO significantly diminished infarct volume and brain water content and improved neurological deficits in a dose-dependent manner. The 25 mg/kg dosage was more effective. Treatment with 25mg/kg TSA significantly improved symptoms and reduce infarct volume at different points in time, of which 10min after MCAO was the most significant. Nissl-staining and HE-staining of the 25 mg/kg TSA group were more appreciable in terms of improvement relative to the vehicle group in the infarct core. TSA of dosage 25mg/kg significantly decreased the expression of cleaved caspase-3 protein and increased the expression of B-cell lymphoma 2 (bcl-2) protein in the ischemic cortex. Fewer terminal deoxyribonucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling (TUNEL)-positive cells were found in the penumbra of the treated group, but they were significantly more common in the vehicle group. We here conclude that the neuroprotective effects of TSA against focal cerebral ischemic/reperfusion injury are likely to be related to the attenuation of apoptosis.