Rotarod and Open Field Test for Behavioral Assessment

We employed a modification of the procedure described by Rozas using a rotarod apparatus (IITC Life Science, Woodland Hills, CA, USA; Rozas et al., 1998). In general, all mice were trained to be accustomed to the rotarod apparatus at low speed rotation before formal experiment. Then each mouse was tested on rotating rods at a rate of six increments (8, 12, 16, 20, 24, 28 rpm) once per day for 3 days. Duration of each speed does not exceed 150 s. At least a 5 min resting period was required between each speed to alleviate mouse stress and fatigue. The overall rotarod performance for each mouse was obtained by plotting the average time on the rod at each speed vs. the rotating speed, and finally calculating the area under the curve (AUC) to evaluate the mice locomotor ability.

Next, we test spontaneous activity in a white open-field box. First the mice were put into the box to make it accustom to the environment for 5 min. Twenty-four hours later, the mice were placed into the same box and let them freely explore for 5 min. The locomotor activity was recorded by a video camera directly above the box and analyzed by a video track system (Noldus Ethovision).