2.4 Morris Water Maze test
Spatial learning and memory were evaluated using the Morris water maze, as described previously (Morris, 1984) with minor modifications. Briefly, the rats were trained for four consecutive days after the last injection of fingolimod or the vehicle. Each rat was trained to find a fixed platform (diameter: 10 cm) hidden 1 cm underneath the water surface, and different geometric shapes on the surrounding walls served as visual cues. Each rat was randomly placed into the water at one of the three starting points and allowed 90 s to find the platform. The time to reach the platform (escape latency) was automatically recorded by the software. Rats that failed to reach the platform within 90 s were manually guided to the platform and allowed to stay on it for 10 s. On the fifth day, the platform was removed and the rats were subjected to a probe trial session. Each rat was released from the opposite platform quadrant and allowed to swim for 60 s. The swimming path, virtual platform crossing time, time spent in each quadrant, and swimming speed of each rat were recorded. Video signals were analysed using EthoVision 7.0 (Noldus Information Technology, Leesburg, VA, RRID: SCR_000441).