Objective:To explore the mechanisms of angiotensinⅡreceptor antagonist(ARB)-induced brain protection by investigating the effect of ARB on the expression of metalloproteinase-2(MMP-2)and matrix metalloproteinase-9(MMP-9)in the brain of renal hypertensive rats after cerebral ischemia-reperfusion.Methods:Thirty-two male Wistar rats were randomly divided into a hypertensive group and a normal blood pressure group.Hypertension was produced by renal artery occlusion.The rats in the renal hypertensive group were randomly sub-divided into an ischemia-reperfusion(hypertension ischemic reperfusion HIR)group treated with normal saline and a HIR valsartan(G)group treated with valsartan(12 mg/kg per day)by gavage for 4 weeks.The normal blood pressure group was sub-divided into a sham operated group(N)and ischemia-repeffusion group(IR).Cerebral ischemia was induced by middle cerebral artery occlusion with suture for 2 hours followed by 22 hours of reperfusion.The expression of MMP-2 and MMP-9 in brain tissue was detected by immunohistochemistry and their gray values were measured using image analysis.Results:The gray values of MMP-2 and MMP-9 in the IR group were significantly higher than those in the N group(P<0.01).The gray values of MMP-2 and MMP-9 in the HIR group were significantly increased when compared with that in the IR group(P<0.05).The gray values of MMP-2 and MMP-9 in the G group were reduced when compared with that in the HIR group(P<0.01).Conclusion:Hypertension aggravates ischemia- reperfusion-induced expression of MMP-2 and MMP-9 in brain tissue.The increased expression of MMP-2 and MMP-9 in brain tissue can be inhibited by angiotensinⅡreceptor antagonist.