Objective:To investigate the effect and the mechanism of parecoxib pretreatment on brain against focal cerebral ischemia-reperfusion injury in rats.Methods:Sixty-four male SD rats weighing 250～300 g were randomly divided into 4 groups(n=16):groupⅠshame operation(S);groupⅡfocal cerebral I/R(I/R);group Ⅲ

Ⅳ parecoxib 5/10 mg/kg +focal cerebral I/R(P5

P10).Middle cerebral artery occlusion(MCAO)models were made by reforming Longa suture method in SD rats.At group Ⅲand groupⅣ

30 minutes before ischemia

inject 5 mg/kg and 10 mg/kg parecoxib injection through the internal jugular vein to the proximal end respectively.GroupⅠ and groupⅡreceived equal volume of normal saline.The infarct volume and the infarct volume fraction were detected by TTC staining

the pathological changes in CA1 region of hippocampus were detected by HE staining

radioimmunoassay technique was used to determine the content of TXA2/PGI2 in brain.Results:Pretreatment with parecoxib

the longa scores、the infarct volume and volume fraction、 the pathological changes in CA1 region of hippocampus、the content of TXA2 in brain and the ratio of TXA2/PGI2 were reduced.Conclusion:Pretreatment with parecoxib can protect the brain from focal cerebral I/R injury by reduced the content of TXA2 in brain and the ratio of TXA2/PGI2.