Memantine increased locomotor activity without severe side effect. (A) Both 5 and 20 mg/kg memantine group increased the distance during the late period of open field test. [Group, F(2, 360) = 26.906, P = 0.000; Time, F(11, 360) = 2.543, P = 0.004; Group*Time, F(22, 360) = 2.810, P = 0.000, two way ANOVA; saline group and 5 mg/kg memantine group, P30 = 0.009, P35 = 0.047, P45 = 0.001, P55 = 0.004, P60 = 0.042; saline group and 20 mg/kg memantine group, P55 = 0.001, P50 = 0.02, P55 = 0.0004, P60 = 0.0008, unpaired Student's t-test; *P < 0.05, **P < 0.01, ***P < 0.001]. (B) Mice injected with memantine spent more time in the center of open field than that of control group mice [group, F(2, 29) = 8.652, P = 0.001, one way ANOVA; post-hoc analysis showed that saline group and 5 mg/kg memantine group, P = 0.069; saline group and 20 mg/kg memantine group, P = 0.015]. (C) Mice injected with memantine spent similar time in open arms with that of saline group mice [group, F(2, 27) = 0.64, p = 0.536, one way ANOVA; post-hoc analysis saline group and 5 mg/kg memantine group, P = 0.412; saline group and 20 mg/kg memantine group, P = 0.290]. (D) LiCl group mice showed significant less distance during the time in open field [group, F(2, 180) = 27.270, P = 0.000; time, F(5, 180) = 20.181, P = 0.000; group*time, F(10, 180) = 0.316; two way ANOVA; saline and LiCl group, P10 = 0.002, P15 = 0.002, P20 = 0.039, P25 = 0.012, unpaired Student's t-test; (D)].