Objective To observe the dynamic changes of brain edema,tumor necrosis factor-α (TNF-α),aquaporin-4 (AQP-4) in focal cerebral ischemia rats and investigate the effect of atorvastatin on the above-mentioned factors.Methods One hundred and eight male SD rats were randomly divided into sham-operated group,model group and treatment group (n=36);furthermore,each group was divided into three subgroups:1 d group,3 d group and 7 d group (n=12).Focal cerebral ischemia models in model group and treatment group were induced by left middle cerebral artery occlusion,while rats in the sham-operated group were only separated from blood vessels with no ligation and no inserted line.After succeeded models,the treatment group received gavage administration of atorvastatin (4 mg/ [kg·d]),others were given the same dosage of normal saline at the same time.The brain edema was calculated by measuring brain water content via dry-wet method,and the mRNA expressions of TNF-α and AQP-4 were detected by real time-PCR;Western blotting was employed to detect the AQP-4 protein expression.Results At the same observation time,as compared with those in the sham-operated group,the brain water content,TNF-α mRNA expression and A QP-4 mRNA and protein expressions in the model group and treatment group markedly increased (P＜0.05);as compared with the model group,treatment group had statistically decreased brain water content,TNF-α mRNA expression and AQP-4 mRNA and protein expressions (P＜0.05).Conclusion The brain edema of focal cerebral ischemia rats may be positively correlated to AQP-4 mRNA and protein expressions induced by TNF-α;atorvastatin probably down-regulates AQP-4 mRNA and protein cxpressions by inhibiting TNF-α to alleviate brain edema and protect brain tissues.