Effect of thymosinβ4 on blood-brain barrier after focal cerebral ischemia and reperfusion injuries in rats

LU Wei-cheng; ZHANG Lu-yang; CHANG Pan-pan; QIU Bo; GUO Zong-ze

doi:10.3969/j.issn.1002-266X.2014.25.006

Abstract：Objective To determine the effect of thymosin β4 on blood-brain barrier ( BBB) after focal cerebral ische-mia and reperfusion injuries in rats , and to explore the mechanism .Methods Seventy-two SD rats were randomly divided into 3 groups:sham operation group (n=24), control group (n=24) and thymosin β4 group (n=24).Focal cerebral is-chemia and reperfusion rat models were made by using the method of thread inserting middle cerebral artery occlusion ( MCAO) , and the brain water content of ischemic tissues was measured 24 h after reperfusion by using the dry-wet weight method.At the same time, the permeability of blood-brain barrier was observed by detecting the content of Evans blue leaked out the brain tissue of ischemic side .The expression of tight junction protein Claudin-5 and matrix metalloproteinase-9 ( MMP-9) mRNA in ischemic brain tissues was detected by RT-PCR.Results Twenty-four hours after cerebral ische-mia and reperfusion injuries , the content of brain water of ischemic side , Evans blue content of ischemic side , and the ex-pression of MMP-9 mRNA significantly increased in the control group as compared with those of the sham-operation group , but the expression of Claudin-5 mRNA decreased significantly .However , the content of brain water of ischemic side , Evans blue content of ischemic side , and the expression of MMP-9 mRNA significantly decreased in the thymosin β4 group as compared with those of the control group , and the expression of Claudin-5 mRNA increased significantly (all P<0.05). Conclusion Thymosin β4 has the protective effect on BBB after cerebral ischemia and reperfusion injuries of rats , whose mechanism may be related to increasing the expression of tight junction protein Claudin -5 mRNA and decreasing the expres-sion of MMP-9 mRNA.