The overall goal of this procedure is to generate a mild traumatic brain injury in juvenile rats. This is accomplished by first preparing the injury induction platform. Next, an anesthetized rat is placed face down on the scored tinfoil.
Once in place, a weight is dropped to generate a glancing blow to the head. The animal is then placed in a supine position, and the time it takes to write itself is recorded. The following day performance is measured on the walking beam test.
So the main advantages of this technique over others is that it's the animals are only briefly anesthetized. It's a closed head injury, which allows us to then repeat the injury in the same animal several times, and there's a rotational component to the injury that is more clinically relevant. The implications of this technique extend towards therapy of pediatric concussion and mild traumatic brain injury because the model induces clinically relevant symptomology in a heterogeneous fashion, demonstrating the procedure will be Irene Ma, a technician in our laboratory and harlene haha.
In undergraduate student in our laboratory. To set up the mild traumatic brain injury apparatus, construct a U-shaped stage made of clear plastic. Place a sponge at the bottom of the stage to collect the animal after it falls.
Next, score a piece of tinfoil with a sharp razor blade. Ensure that the scored tinfoil supports the body weight of the rat, but will not interfere with acceleration following impact. Tape the scored tinfoil on top of the stage so that it is tau, and place it in the correct position underneath the guide tube.
Position the guide tube so that it is 3.5 centimeters above the tinfoil. Next, attach fishing line to the top of a weight. Place the weight inside the guide tube and fix the line so that the weight hangs 2.5 centimeters above the foil.
This height prevents the rat from receiving multiple hits securely. Attach the fishing line to the clamp stand. Pull the weight up through the plastic guide tube with the fishing line and hold it in place with an Allen key pin positioned at a height of 0.5 meters.
To begin, confirm the depth of sedation in an anesthetized rat and quickly place the rat chest down on the foil with its head directly in the path of the falling weight. When ready to begin, pull the Allen key pin to allow the weight to fall vertically through the plastic guide tube. Once struck, the rat will rapidly undergo a 180 degree rotation and land in the supine position.
Immediately remove the rat from the collection sponge and apply topical lidocaine to the rat's head with a cotton tipped applicator. Next, place the rat in the supine position in a clean, heated cage. Observe the animal until it wakes from the anesthetic and flips from the supine to the prone position.
Record this as the time to write value for the sham injured control group. Anesthetize the animal and place it on the stage as demonstrated earlier. Next, remove the rat from the tinfoil without pulling the Allen key pin and apply topical lidocaine to the head.
Place the rat in the supine position in a clean, heated cage and record the time to write value. Lastly, return the rat to its home cage after it has recovered normal behavior and repeat with the next control animal. 24 hours after the induction of brain injury, return the animals to the procedure room.
Transfer the rats to a clean holding cage and place the rat's home cage. At the narrower end of a tapered beam face, the open-ended part of the cage toward the wide end of the beam. The tapered beam has a center platform with small ledges that provide safety.
Place a video camera at the wide end of the beam and adjust the focus until the entire length is visible. When ready, place the rat at the wide end of the tapered beam and encourage it to walk across the beam towards its home cage. Once the rat crosses the beam and enters the home cage, let it rest for at least 60 seconds.
To reinforce the target location, this is trial number one and is not included in the analysis. Next, turn the video camera on and allow the rat to complete the beam walking task for additional times, maintaining the 62nd reinforcement periods in the home cage. Once the rat has completed all trials, return it to the home cage and test the next animal.
If the animal falls off the beam during testing, immediately pick it up and place it back onto the beam in the location from which it fell. To score the data. After testing, record the number of hind leg foot slips and the total time to cross the beam for each individual trial.
Use this data to compute average values for each animal and test group. This graph compares the average differences in time to write scores between juvenile rats that experienced a single brain injury compared to sham controls. Injured rats exhibited a significant increase in the duration of time needed to write themselves from the supine position.
Here, the average number of hind leg foot slips on the beam walking task is shown for the juvenile rats that experienced a single injury. Compared to sham injured rats, injured animals exhibited significantly more foot slips across the beam compared to controls Following this procedure. Other non-invasive interventions such as play therapy, can then be explored to determine whether such interventions are actually able to ameliorate some of the social deficits that kids experience following.Concussion.
After watching this video, you should have a good understanding of how to safely induce and detect a mild traumatic brain injury in juvenile rodents. That can be repeated at multiple time points.
