Objective To observe the curative effect of puerarin on Alzheimer's disease (AD) in ovariectomized versus non-ovariectomized rat.Methods 100 6-month-old female SD rats were randomly divided into 5 groups:the control group,non ovariectomized AD group,ovariectomized AD group,non-ovariectomized AD treatment group and ovariectomized AD treatment group (n =20each).Rat model of AD was made by treating with combined D-galactose and sodium nitrite for 60days.Treatment group rats were treated with puerarin for 8 weeks.At the end of the experiment,rats learning and memory abilities were tested by water maze,the serum estradiol,progesterone,follicle stimulating hormone and luteinizing hormone were measured,and the activities of cholinesterase (TchE) and superoxide dismutase (SOD),malondialdehyde (MDA) concentration in brain homogenate were determined.Results Compared with the control group,TchE activity and MDA content were increased,and SOD activity was reduced (all P＜0.01),and learning and memory abilities were significantly decreased in the ovariectomized and non-ovariectomized AD groups.Compared with the model groups,the activity of TchE and MDA concentration were reduced,and SOD activity was increased (all P＜0.01),and learning and memory abilities were significantly improved in the two treatment groups.As compared with non ovariectomized AD treatment group,the increase in SOD and TchE activities and decrease in MAD concentration were much more in ovariectomized AD treatment group (P＜0.05),and the improvement in learning and memory abilities was more significant.Conclusions Puerarin has a therapeutic effect on rat model of AD,even better on the ovariectomized rat model of AD.