Morris water maze test

After 10 weeks of exercise, the mice had 1 week of rest. Then the Morris water maze task was used to evaluate the spatial memory performance of the animals (Morris, 1984; Li et al., 2015). The water maze required the mice to swim and find a submerged platform 1 cm below the surface of the water for safety. The pool had a diameter of 1.20 m and a depth of 0.5 m, and was filled with 30 cm of water at 22–24°C. For each trial, a mouse entered the pool from an ambulatory position for a maximum of 2 minutes. The mouse used spatial cues held at fixed positions in the room to find the escape platform. If the platform was not located in time, the mouse was directed to the platform and allowed to stay there for 15 seconds. Two trials were conducted per day for each animal with an interval of 2 hours between trials for 7 days. All trials were recorded by a monitor system (Nodulus, Wageningen, Netherlands). For data analysis (escape latency, distance moved), the last 5 days’ test records were used.