(A, B) After the visible platform test, the rats were submitted to the transfer acquisition phase of Morris water maze test for four consecutive days, and the latency traveled to find the hidden platform (A) and the distance swam in searching for the hidden platform (B) in the transfer acquisition phase were recorded. (C, D) After the transfer acquisition phase of Morris water maze test, the rats were submitted to the transfer probe phases of Morris water maze test, and the number of times that the animal crossed the target quadrant platform area (C) and the percentage of time spent in the target quadrant (D) were analyzed. The data are expressed as the mean ± S.E.M. (n=7-12). *P< 0.05, ***P< 0.001, versus control group; #P< 0.05, ##P<0.01, ###P< 0.001, versus the STZ-treated alone group.