The Effects Of Brain-derived Neurotrophic Factor During Fracture Healing In Brain Injury Associated With Fracture

Objective:To study the effects of brain-derived neurotrophic factor during fracture healing in brain injury associated with fracture.Methods:Fifty-eight adult health Sprague-Dawley(SD) rats were randomly divided into two groups:(1) fracture group(F n=28), (2) trumatic brain injury associated with fracture group(BF n=28).Simple tibial fracture model was set up in the first group.Traumatic brain injury associated with fracture model was set up in the second group.S-D rats were killed respectively on 1st,2nd,3rd,4th week after operation. The animals were killed in 3rd and 4th week after X-ray examination.After excution,bone tissue,periosteum and bone callus in fracture site were taken to be made into paraffin sample.It was cut into slices.After HE was dyed slices were oberved under the mere mirror.BDNF and TrKB expression changes in callus tissue were tested at each fracture healing time point by immunohistochemical method.Analyse and process statistics in data.Results:1.X-ray findings:BF group has more bony callus than F group in 3rd week, and its fracture line is more ambiguous in 3rd week.BF group was better than F group in fracture remodeling in 4th week,and fracture line almost disppeared in 4th week.2.Expression of BDNF:â‘ F group:BDNF expression is detected in osteoblast, chondrocyte and fibroblast in bony callus, and its expression increase with time.â‘¡trauma combined with fracture group: The expression of BDNF in osteoblast, chondrocyte and fibroblast peaked during the first week after surgery, then mild decreased during the second week. There is significant difference of the expression of BDNF in osteoblast, chondrocyte and fibroblast between cerebral trauma combined with fracture group and closed fracture group. However, the expression of BDNF in osteoblast, chondrocyte and fibroblast decrease during the third and fourth week with time, and the difference between cerebral trauma combined with fracture group and closed fracture group disappeared.3.The expression of TrkB:â‘ fracture group:TrkB expression is detected in osteoblast, chondrocyte in bony callus, and its expression increase with time,â‘¡brain trauma combined with fracture group:The expression of TrkB in osteoblast, chondrocyte peaked during the first week after surgery, then mild decreased during the second week. There is significant difference of the expression of BDNF in osteoblast, chondrocyte between cerebral trauma combined with fracture group and closed fracture group. However, the expression of BDNF in osteoblast, chondrocyte decrease during the third and fourth week with time, and the difference between brain trauma combined with fracture group and fracture group disappeared.Conclusions:Tibial fracture heals faster when combined with brain injury.It may be associated with the expression up-regulation of BDNF and its receptor TrkB in callus of fracture sites.