*2.7. Morris Water Maze Experiment*

A Morris water maze (MWM) experiment was conducted in submerged platform following standard procedures and it was conducted after TST. The hidden-platform was fixed in the center of one of quadrants and 1.5 cm below the water surface. Mice underwent three trials each day for 6 days. Each time, mice were placed into the water from other three quadrants. Before and after each test, mice were placed on the platform to adapt for 20 s. Mice that remained on the platform for more than 5 s were considered to have searched platform successfully during the 90 s of detection. The mice were deeply anesthetized and sacrificed by cervical dislocation after MWM test was finished.

Once the mice were sacrificed, the hippocampal tissues were quickly dissected and immersed immediately in liquid nitrogen and then transferred to refrigerator at −80 ◦C until being used.
