Basic NeuroscienceA novel traumatic brain injury model for induction of mild brain injury in rats

- Mild TBI constitute approximately 80% of all traumatic brain injuries in humans.
- Improved animal models that mimic all aspects mild TBI in humans are needed.
- A novel stereotaxic coupled weight drop device was designed.
- The new device induced both primary and secondary damages at trauma site.
- This new model of TBI is suitable for evaluation of mild TBI.

BackgroundDue to the marked heterogeneity of human traumatic brain injury (TBI), none of the available animal model can reproduce the entire spectrum of TBI, especially mild focal TBI. This study was designed to develop a modified TBI weight drop model for induction of focal mild cerebral injury.New methodA stereotaxic coupled weight drop device was designed. Principle arm of device carries up to 500 g weights which their force was conveyed to animal skull through a thin nail like metal tip. To determine the optimal configuration of the device to induce mild TBI, six different trials were designed. The optimal configuration of the instrument was used for evaluation of behavioral, histopathological and molecular changes of mild TBI.ResultsNeurologic and motor coordination deficits observed sharply within 24 h post injury period. Histological studies revealed a remarkable increase in the number of dark neurons in trauma site. TBI increased the expression of apoptotic proteins, Bax, BCl2 and cleaved caspase-3 in the hippocampus.Comparison with existing methodsOur designed TBI device is capable to produce variable severity of TBI from mild to severe. The main advantage of the new TBI model is induction of mild local unilateral brain injury instead of traumatization of the whole brain. This model does not require craniotomy for induction of brain injury.ConclusionThis novel animal TBI model mimics human mild focal brain injury. This model is suitable for evaluation of pathophysiology as well as screening of new therapies for mild TBI.