Objective: To investigate the effect and possible mechanism of Qingre Huayu prescription on oxidative stress in rats with cerebral ischemia-reperfusion injury (I/R) through nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway. Method: The focal cerebral ischemia rat (MCAO) model was prepared by suture method

and 160 SD rats were randomly divided into 4 groups:sham operation group (SO)

model group (MCAO)

Qingkailing control group (QKL)

and Qingre Huayu prescription group (QRHY)

n=40 in each group. Each group was further divided into 4 subgroups according to 12 h

1 d

2 d and 3 d after I/R

n=10 in each sub group. Cerebral infarction volume was tested by triphenyltetrazolium chlorid(TTC) staining method

and the changes of the mRNA and protein expression of Nrf2 and heme oxygenase 1 (HO-1) at each time point after reperfusion were observed by real-time fluorescence quantitative PCR(Real-time PCR) and immunohistochemistry separately. Result: As compared with the normal group

the brain infarct volume was significantly increased in MCAO group 1 d after cerebral ischemia reperfusion (P<0.01); the brain infarct volume in QKL group was significantly smaller than that of MCAO group (P<0.05

P<0.01); QRHY could further decrease the brain infarct volume as compared with QKL group (P<0.05). The mRNA and protein expression levels of Nrf2 and HO-1 in MCAO group were increased significantly 12 h after I/R

and reached the peak at 24 h (P<0.05

P<0.01)

then decreased continuously with the increase of I/R time

but still maintained high expression levels (P<0.05). QKL could increase the mRNA and protein expression levels of Nrf2 and HO-1 as compared with MCAO group (P<0.05). QRHY could further increase the above expression as compared with QKL group (P<0.05). Conclusion: QRHY may up-regulate the expressions of Nrf2 and HO-1 in rats and relieve I/R through activating the Nrf2/ARE signaling pathway.