Abstract: Objective This study is to explore the protective role and mechanism of tanshinoneⅡA(Tan ⅡA)for the blood-brain barrier in focal cerebral ischemia of rats. Methods Male Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion(MCAO). Sprague-Dawley rats (n = 168)were randomly divided into sham-operated group,MCAO group,TanⅡA higher dose group (TanⅡA-H)and TanⅡA lower dose group(TanⅡA-L). Tan ⅡA was administered with intraperitomeal injection immediately after operation,rats were executed at 24h. Western Blot,RT-PCR and confocal microscope were used to measure claudin-5 protein and IgG expression in ischemic brain. And the neurological deficits,brain water content and infarct volume were explored. Results At 24h after focal cerebral ischemia,claudin-5 expression in MCAO group decreased. Claudin-5 in Tan Ⅱ A-H group significantly up-regulated,and also its neurologic deficit,infarct volume and brain water content were alleviated compared with MCAO group( P ﹤ 0. 05). Conclusion Tan Ⅱ A-H protected blood-brain barrier permeability by increasing claudin-5,which might be the mechanism of treating focal cerebral ischemia.

Key words: brain infarction, blood-brain barrier, tanshinone