Abstract: Objective To investigate the effect of Lycium barbarum extract on learning and memory function and its mechanism in natural aging mice.Methods Sixty male Kunming mice of 12-month old were randomly divided into an aging control group and low,moderate,and high Lycium barbarum groups with intragastric administration of Lycium barbarum extract(0.1 ml/10 g·day) for 17 weeks; another 15 male Kunming mice of 2-month old were used as an adult control group.Learning and memory function of the mice were determined by Morris water maze and enzyme-linked immunosorbent assay(ELISA)method was used to measure muscarinic acetylcholine receptor M1(M1R) content in hippocampus tissues of the mice.Results The results of place navigation test at 5th day showed that the escape latency period for the mice of low,moderate,and high Lycium barbarum groups were 41.07±8.85,38.13±11.81,and 37.51±9.47 seconds,and significantly shorter than that of the aging control group(44.81±7.84 seconds)(all P<0.05).In spatial probe trial,the mice of low,moderate,and high Lycium barbarum groups showed significantly higher percentages of active time in the target quadrant(31.65±6.19%,36.34±7.62%,and 38.75±5.35%) and the times of across the platform(3.09±0.63,3.89±0.47,3.51±0.28,and 3.89±0.47 times)than those of the aging control group(28.82±3.18%,2.13±0.32 times)(all P<0.05).The concentration of M1R in hippocampus tissue for the mice of low,moderate,and high Lycium barbarum groups were 1137.84±339.63,1219.35±307.49,and 1325.81±327.76,1325.81±327.76 pg/mL and significantly higher than that of the aging control group(976.42±321.37 pg/mL)(all P<0.01).Conclusion Lycium barbarum extract could improve the learning and memory function in natural aging mice and the mechanism of the effect might be associated with the increase of M1R concentration in hippocampus tissue of the mice.