Aim:To explore the influence of different doses of D-galactose on learning memory capacity in mice.Methods:The 2-month-old KM mice were randomly divided into D-galactose-treated groups (75,100,150,300 mg·kg^-1) and normal control group,with 12 mice in each group.The corresponding dose of D-galactose was administered subcutaneously to the back of the neck,and normal control group was injected subcutaneously with saline for 8 weeks.Learning memory capacity of mice was detected through Morris water maze,step-down passive avoidance test and new object recognition test.Meanwhile,the enzymatic indicators in the brain were determined to detect the damage degree in mice with different doses of D-galactose.Results:Compared with the normal control group,the spatial and non-spatial cognitive functions and brain enzyme levels of D-galactose in each dose group was damaged to varying degrees,especially the dose of 100 mg·kg-1 group.In the water maze experiment,D-galactose groups significantly prolonged the time of crossing the platform for the first time and decreased the number of crossing platforms,especially at the dose of 100 mg·kg-1 (P < 0.05);in the new object recognition experiment,discrimination index was significantly decreased in each D-galactose group (P < 0.01),and the dose of 100 mg·kg-1 was most obvious;in addition,D-galactose could significantly increase the level of acetylcholinesterase (AChE)(P < 0.01),decrease the levels of superoxide dismutase (SOD),glutathione peroxidase (GSH-Px),and total antioxidant capacity (T-AOC)(P < 0.05 or P < 0.01) in the mice brain.Conclusion:Subcutaneous injection of low-medium-high dose of D-galactose for 8 weeks in the back of the neck can cause changes in brain parameters in mice,but the effects of different doses of D-galactose on some indicators are significantly different.D-galactose model is effective and stable at the dose of 100 mg·kg-1.