Cognitive impairment displayed by ApoE knockout mice in the Morris water maze

Objective:To observe the cognition of ApoE knockout (ApoEKO ) mice. Method:Three-month old male ApoEKO mice and C57BL6J mice were tested by Morris water maze. All animals were tested for seven consecutive days, in which escaping latency and swimming track were recorded automatically, and the time spent in the target quadrant was obtained. On the eighth day the platform was removed and the percentage of time spent in different quadrants was analyzed. Result:Both groups reduced their latencies across days. But in the early stage of the test, ApoEKO mice displayed much longer latencies and spent less time in the target quadrant than C57BL6J mice. The performance of both groups were indistinguishable toward the end of the test. Conclusion:ApoEKO mice displayed cognitive impairment in the Morris water maze,especially in the early stage of the acquisition phase. But they were eventually able to learn the task with more training sessions.Author′s address Qingdao Hiser Hospital, 266034