Objective:To investigate the effect of ginsenoside Rb1 (GRb1)on glial fibrillary acidic protein (GFAP) and regional cerebral blood flow(rCBF) in cortex of rats and explore its possible mechanism by using photochemically induced local cerebral ischemia model. Method:Forty-eight SD rats were randomly divided into model group

sham operation group

GRb1 high dose group (100 mg·kg-1)

medium dose group (50 mg·kg-1)

and low dose group (25 mg·kg-1)

as well as nimodipine group (1 mg·kg-1)

with 8 rats in each group. The changes of regional cerebral blood flow in the right cerebral cortex were measured by laser Doppler flowmetry after ischemia for 24 h. The expression of GFAP mRNA was detected with Real-time PCR method

while Western blot and immunohistochemistry method were used to detect the expression of GFAP protein. Neurological function of rats was detected by using the neurological behavior score. Result:As compared with the sham operation group

the cerebral blood flow was decreased significantly in the model group (P<0.01). As compared to the model group

the neurological function deficits were decreased in high dose GRb1 group (P<0.05) and the cerebral blood flow was increased significantly in GRb1 groups (P<0.05). The expression levels of GFAP mRNA and protein in model group were significantly higher than those in sham operation group(P<0.05). As compared with the model group

GRb1 groups can respectively increase the positive expression of GFAP (P<0.05)

especially in high dose group (P<0.01); there was no significant difference between GRb1 high dose group and nimodipine group. Conclusion:GRb1 can increase regional cerebral blood flow

up-regulate the expression of GFAP

protect the morphology of astrocytes

and reduce the damage of ischemic penumbra neurons in acute cerebral ischemia stage.