After dividing the rats into a control, or a CON, and model, or MOD group, house them in individual cages. For the open field test, partition a black box into 25 square sections of equal area. Install a video tracking analysis system in the box.
Place the rat in the central square and monitor its horizontal and vertical activities for five minutes. After the test, sanitize the box with 75%alcohol to remove any remaining rat odors. To assess anhedonia through the sucrose preference test, weigh bottle A containing water and bottle B containing 1%sucrose.
Place both bottles on the cage lid and allow ad libitum access to both solutions for the rat. After consumption, weigh the bottles, and, using the given formula, calculate the 60 minute sucrose preference rates on given days. To perform the Morris water maze test, divide the pool into four quadrants, and number them from one to four.
In the third quadrant, place a resting platform one centimeter below the water surface. Add milk to the pool to increase water opacity and maintain a water temperature of approximately 23 degrees Celsius throughout the experiment. Place the rat in one quadrant of the maze, and using the Morris Water Maze video tracking system, record the latency time to identify the platform for 120 seconds.
Finally, remove the hidden platform from the pool. Then, place the rat into the water and record the number of zone crossings for 120 seconds. In the open field test, the MOD group exhibited lower vertical and horizontal scores compared to the CON group, indicating successful induction of anxiety.
After 28 days, the MOD group showed a lower sucrose preference percentage than the CON group. The Morris water maze test revealed that the MOD group had a longer latency to locate the platform and crossed fewer times compared to the CON group. Further, the MOD group exhibited reduced hippocampal 5-HT levels compared to the CON group.
