An experimental multifaceted traumatic brain injury model

Study objectives: Traumatic brain injury (TBI) triggers an inflammatory cascade that results in increased blood-brain barrier permeability, edema, and infiltration of leukocytes leading to neuronal cell death. The fluid percussion head injury (FPI) model will be used to reproduce TBI in the rat to follow biochemical, histologic, and behavioral changes and to test new drugs with beneficial therapeutic effects. Methods: Wistar rats (250- to 300-g body weight) were anesthetized with halothane, and a 4-mm craniotomy was done on the right parietal cortex. A 2-mm female union bolt was cemented to the skull, and animals were left to recover for 24 hours before the FPI (3 atm, 100-ms duration). Animals were left for different periods, up to 7 days with food and water ad libitum. Blood-brain barrier permeability was evaluated at 24, 48, and 72 hours after FPI by measuring Evans Blue dye extravasation. Neurologic scoring of motor skills was evaluated with the Rotating Pole test and the Ladder climb test. Immunohistochemistry performed with paraffin embedded 10-μm sections using terminal deoxynucleotide transferase–mediated dUTP nick-end labeling (TUNEL) and glial fibrillary acid protein (GFAP) staining in the core region. Results: The level of Evans Blue recovered from the damaged (right) hemisphere was increased 3.9- and 5.0-fold at 24 and 48 hours, respectively, whereas in the contralateral hemisphere, these values were 3.3- and 2.4-fold, indicating a lower, although significant, alteration of the blood-brain barrier and a faster recovery than in the damaged site. Rotating pole results demonstrate that the TBI model produces significant motor function impairment compared with control and sham groups. Histologic examination by TUNEL 48 hours after trauma showed the area of apoptotic cell death, and by 7 days reactive gliosis was detected with GFAP in the FPI area. All studies were done in parallel in sham control animals. Conclusion: This model having been validated, studies are currently under way to investigate new neuroprotective compounds used for the treatment of the devastating effects of TBI in human beings.