The Morris Water Maze Test

Morris water maze (MWM) tests were carried out 2 months after surgery to evaluate cognitive performance of each group as previously described (Gao et al., 2016). Briefly, A 120 cm diameter tank was filled with water with non-toxic milk powder dissolved in it. The pool was divided equally into four quadrants: northeast (NE), southeast (SE), southwest (SW) and northwest (NW). The circular platform was 10 cm in diameter located in the center of NE quadrant, and was submerged 1.5 cm below the surface of water. Several visual cues were placed in the room as spatial reference for mice to locate the invisible platform, and experimenter remained stationary in a fixed location. After 5 days of acquisition trials, the platform was removed and mice were placed in the SW quadrant, opposite to the former platform position and the probe trial underwent. During the whole trials, all mice were maintained on their western type diet. Behavioral parameters (latency; percentage of time and distance in the NE quadrant; the number of times the mouse crossing over the position of the platform) were recorded and evaluated with AVTAS software.