Objective:To observe the effect of Erxiantang on ovariectomized-induced cognitive impairment in rats. Method:Female SD rats were randomly divided into sham group

control group

positive estradiol valerate group (0.8 mg·kg-1·d-1)

low-dose Erxiantang group (equivalent raw drug dosage of 12 g·kg-1·d-1)

medium-dose Erxiantang group (equivalent raw drug dosage of 8 g·kg-1·d-1)

and high-dose Erxiantang group (equivalent raw drug dosage of 4 g·kg-1·d-1). The rats were ovariectomized except for the sham group rats. All of the animals were administered with drugs for 90 days after vaginal smear screening. The cognitive ability of rats was evaluated by the Mirrors water maze test. The contents and active of acetylcholinesterase (AchE)

acetylcholinesterase (ChAT)

total superoxide dismutase (T-SOD)

and malondialdehyde (MDA) of rat cerebral cortex were detected by colorimetry. The expression of estrogen receptor protein in the hippocampus and the cortex regions were detected by Western blot. Result:Compared with the sham-operated group

the escape latency of the model group increased significantly with the rise in the number of trials (P<0.01)

the residence time in the original platform quadrant was decreased (P<0.05)

the activity of ChAT was decreased (P<0.01)

the activity of AchE was increased (P<0.05)

and the expression of estrogen receptor α in the cerebral cortex was significantly reduced (P<0.01); compared with the control group

the rats escape latency in control groups was shorten by Erxiantang. The frequency of passing through the original target platform and the ratio of residence time in the original target platform quadrant increased. The activity of ChAT increased significantly

while the activity of AchE decreased. The expression of estrogen receptor α significantly increased (P<0.01). Conclusion:Erxiantang can improve the cognitive impairment in ovariectomized rats

and the mechanism may be related with cholinesterase and estrogen in central nervous system.