Objective: To observe the effects of Huannao Yicong Prescription(HYP) on learning and memory impairment

level of brain β-amyloid Protein (β-AP)and substance P(S.P)in aging rats. Methods: Morris water maze test was used to measure the spatial learning and memory of rats. 40 rats with learning and memory impairment were divided randomly into four groups (10 in each group):the model group (learning and memory impairment aged rats group)

the high-dose HYP group (13.68 g crude drug/kg)

the low-dose HYP group (6.84 g crude drug/kg)

the positive control group (Hydrochloricdonepezil Tablets 0.45 mg/kg)

besides

a normal aged rats group with 10 rats was set up

they were given tales doses of distilled water

all other groups were orally administered with drugs for 8 weeks. Then the spatial learning and memory of rats were measured again by Morris water maze. Rats were sacrificed after anesthesia and the brain homogenate was made for measuring the content of β-AP and S.P. The activity of superoxide dismutase (SOD) and the content of maleic dialdehyde (MDA) in serum was measured

the histomorphological changes in the brain were observed after hematoxylin eosin (HE) staining. Results: The latency and path length in water maze test in the model group were significantly prolonged. After 8 weeks of administration

the latency and path length in both of the HYP groups were significantly shortened than the model group

and the strategy in finding the platform was improved. Compared with the normal aged rats group

the content of MDA was significantly increased while the activity of SOD was significantly decreased in the model group. After 8 weeks of administration

compared with the model group

the level of β-AP was decreased while the S.P was increased

the activity of SOD was significantly increased(P<0.01)and the histomorphology in the brain was improved in the HYP groups. Conclusion: HYP can reduce the deposition of β-AP in the brain tissue

protect the integrity of histomorphology in the hippocampus

and thus improve the spatial learning and memory for aged rats.