After inducing a mild traumatic brain injury in an anesthetized rat, position it on its back inside a clean cage. Place foam padding beneath the balance beam to reduce the risk of injury to the rats in case of falls during the test. Place an escape box at one end of the beam.
Activate the video camera to record the test. Once the animal recovers, position the rats at the other end of the balance beam. Position the rats on the two centimeter wide beam for a series of five consecutive trials.
Record the initiation and conclusion of each trial when the rat's nose crosses the starting and finishing lines respectively. Prepare the open field arena, ensuring it is clean and devoid of any prior odor cues. Divide the arena into three distinct zones:a central inner zone, a middle zone, and an outer zone.
Place a rat in the center of the open field arena and initiate the timer. Allow the rat to freely explore the arena for a duration of five minutes. After this period, carefully and gently return the rat to its home cage.
Quantify the total distance covered by the rat during the five-minute exploration period. Additionally, determine the amount of time the rat spends in the three zones. Ensure that the water maze apparatus is in proper working condition.
Place the platform at a depth of 2.5 centimeters below the water surface. Dye the water black and position cues in the four cardinal directions. Establish a monitoring system to record and observe the behavior of the rats.
Then introduce the rat into the water maze. If the rat is unable to reach the platform within a two-minute timeframe, gently guide it using a wooden stick. Allow the rat to become accustomed to the maze environment while standing on the platform for a duration of 20 seconds, then remove it.
On the sixth day, which is the probe test day, remove the platform from the water maze and position the rat in the same quadrant for a duration of two minutes. Employ the monitoring system to continuously observe and record the rat's behavior. Motor coordination was assessed pre and post-anesthesia or injury using the beam task.
At day one post-injury, mTBI rats showed significantly more hindlimb slips compared to shams. However, after two days, hindlimb slips returned to sham levels. All six mTBI rats had more post-impact hindlimb slips with no differences in beam traversal times between mTBI and sham rats.
Distance traveled showed no significant differences between sham and mTBI groups. Anxiety-like behavior was evident in mTBI rats at three and seven days post-injury, spending less time in the center zone during the open field test. Morris water maze results indicated impaired spatial learning and memory in mTBI rats.
They took longer to find the hidden platform and spent less time searching for the removed platform during the probe trial without differences in swimming speed suggesting no impact on spontaneous locomotor function.
