Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

In this study, we would like to demonstrate an investigation of dominant-submissive relationship through tests based on food competition. The overall goal of the current study is to show the development of dominant-submissive relationship after traumatic brain injury. The advantages of this method are its easy reproducibility and the ability to observe and accurately analyze dominant-submissive behavior.

The dominant-submissive method is well represented in the literature and has been applied as a model to assess mania and depression. This model has been used to investigate early life stress after maternal separation in adult rats as well. To begin, select 30 adult males randomly.

Divide them into traumatic brain injury and sham groups. Provide chow and water ad libitum. Before the injury, perform baseline assessments of the neurological severity score in both groups of rats as described in the manuscript.

After anesthetizing the rats, check for the immobilization of the rat by testing for lack of movement or pedal reflex in response to a stimulant. Perform craniotomy four millimeter posterior and four millimeter lateral of bregma. Using a fluid percussion device, induce traumatic brain injury over 21 to 23 milliseconds through the three-way stopcock.

Perform craniotomy on the group of sham operated rats and infiltrate 0.1%bupivacaine before closing the wound. One week before the test, randomly divide the rats into cages. Use an apparatus made from two transparent acrylic glass boxes connected by a slender tunnel.

Next, fill a feeder with sweetened milk and place it in the tunnel center. Place each rat in the apparatus for 15 minutes for habitation on the first two days. Randomly select one rat from the control group and one from the traumatic brain injury group and set them at equal distances from the feeder, allowing them to explore for five minutes.

Allow the rats access to water ad libitum. Position a camera. Install the recommended computer software to capture, save, and process the data, and record the video while the rats are in the arena.

The neurological severity score showed that 48 hours after surgery, the neurological deficits were sufficiently greater for the traumatic brain injury rats compared to the sham operated rats. However, 28 days after surgery, the differences between the traumatic brain injury and sham operated groups were insignificant. Time spent at the feeder was significantly lower for the traumatic brain injury rats compared to the sham operated rats.

Fewer traumatic brain injury than sham operated rats came first to the feeder. The most important things are cleaning the apparatus before every session and performing the test in a room with proper air circulation. This technique paves the way for researchers to explore dominant-submissive behavioral in rats after brain injury.