Objective To study the effect of atorvastatin on MMP-9expression in I/R rats.Methods Ninety-six SD rats were randomly divided into sham operation group(n=16),I/R group(n=40)and atorvastatin treatment group(n=40).A middle cerebral artery I/R model was established.Rats in atorvastatin treatment group were treated with oral atorvastatin 21 days before I/R model was established.Rats in sham operation group were further divided into 24 hgroup and 48 h group and those in I/R group and atorvastatin treatment group...