2.3. Behavior Testing

In order to see if the rats were prone to depression, the sucrose preference test was applied. We referred to the method in [28] and improved it appropriately. Before starting the test, rats were kept in quiet rooms and adapted to the sucrose solution. First, we prepared two bottles of 1% sucrose solution for rats to drink for 24 h, followed by one bottle of 1% sucrose solution and one bottle of pure water for 24 h, and changed the positions of the two bottles at the intermediate point of time. Rats were banned drinking water for 24 h, and their preference was tested for sucrose solution. In this experiment, all rats were kept in a single cage for 24 h and prepared with two bottles of water which were weighed before the experiment, and the amount of sucrose solution the rats drank was calculated by the difference between weight before and after the test. The sucrose preference was calculated as follows: sucrose preference (%) = sucrose consumption (g)/(sucrose consumption (g) + pure water consumption (g)) × 100%.

Each rat was placed into a cylindrical container; the container was 11 cm in diameter, 25 cm in height, and 20 cm in the depth of the water (25 ± 1 °C). The test duration was 6 min, and the time of the experiment was recorded by two trained students [29]. The rat was quiescent, and the body did not struggle as a standard of immobility. After the experiment, the rats were dried with a towel.

This test is intended to test if the animals exhibit a depression-like behavior, using a square box (100 × 72 × 40 cm) and a mobile phone. Rats were put in the center of the box, respectively, followed by mobile phone shooting and timekeeping at the same time, which stopped after 5 min. The number of horizontal movements and the number of vertical movements were recorded by using the mobile phone, respectively [29]. After testing each rat, the inside and bottom of the box were thoroughly cleaned with alcohol so as not to affect the next test result.