Experiment Study Of Expression Of BDNF And The Postmortem Stability After Traumatic Brain Injury In Rat

Background and objective: Traumatic brain injury is the most common injury in traffic accidents and other machinery, how to make use of objective methods and standards estimated injury interval has been a major problem in forensic medicine. Brain-derived neurotrophic factor (BDNF ) was one of the neurotrophic factors, which micro-expressed in the normal brain tissue, and expressed after brain injury. It not only can protect neurons, but also can promote nerve cell differentiation and regeneration of brain function. After brain injury it played an important role in the injury recovery. In the current domestic and international studies on the BDNF, more focused on its role in the treatment of nerve injury, and the studies on the expression and postmortem stability of endogenous BDNF at different times after traumatic brain injury were few. After traumatic brain injury, further study on the expression and postmortem stability of BDNF, may provide a new index to estimate the injury interval and identify brain injury for forensic medicine.Methods: 105 SD rats, weight (270±30) g, of either sex, were randomly divided into normal group, sham-operation group, traumatic brain injury group, and postmortem stability group. The model of traumatic brain injury was established by the free-falling-body impact device according to the Feeney method. The samples surrounding the lesion were harvested at different time points. The brain tissue of paraffin wax slices were prepared for HE staining and microscope observation. The expression of BDNF protein at different time were detected by immunohistochemical technique. The results were analyzed by SPSS 10.0 software.Results: In normal group and sham-operation group the BDNF protein was weakly positive expressed. In traumatic brain injury group, positive expression of BDNF can be detected 0.5 hour after brain injury, after that the expression gradually increased and get to a peak at six hours after brain injury, and decreased to basic level 24hours after injury. In postmortem stability group, the expression of BDNF shows no difference between 1day and 7days after death.Conclusions: The expression of BDNF quickly increased after traumatic brain injury was associated with the time, and show some regularity. The BDNF expressed stably after death, it can be used as a referenced index to estimate the injury interval within 24 hours after brain injury.