A new model of traumatic brain injury with varying degree of severity in rats

Objective To establish and evaluate traumatic brain injury model with varying degrees in rats. Methods Twelve rats were randomly divided into three groups (mild group, moderate group, severe group). Controlled cortical impact (CCI) device was used to cause brain injury in rat model by different impact heads (mild group: diameter = 2 mm, moderate group: diameter = 2.5 mm, severe group: diameter = 3 mm) and different impact depth (mild group: 2-3 mm, moderate group: 3-4 mm, severe group: 4-5 mm) with impact duration of 0.1 s and impact velocity of 2.5 m/s. After modeling, brain histopathology changes were observed to make sure if modeling was successful. Magnetic resonance imaging (MRI) scan was performed and the Revised Neurobehavioral Severity Scale (NSS-R) was used to evaluate the extent of brain injury of three groups accurately. Results After modeling, all rats showed abnormal behaviors. In the damaged regions, the number of neuron decreased, with diffusive infiltration of microglia, congestion, vacuolar degeneration in various cells. The total volume of injury brain of mild group was (11.33±1.11) mm³, (20.77±1.90) mm³in moderate group and (46.19±12.79) mm³in severe group. Conclusion Traumatic brain injury models with varying degree of severity are established successfully in rats by application of CCI device, and the degree of injury is assessed by different methods with quantifiable, stable and repeatable results, which can be the groundwork for further study.