Abstract: Objective To investigate the effect of exercise training on the expression of BDNF (brain-derived neurotrophic factor) and tyrosine kinase receptor B(TrkB) in spinal cord of spinal cord injury(SCI) rats. Methods Spinal cord injury models were produced by universal spinal cord impact system. Twenty-four female adult Sprague-Dawley rats were randomly divided into 3 groups, exercise group (SCI-induction and exercises group, n=8), control group (SCI-induction without exercises group, n=8) and sham-operation group (no operation, without SCI and exercises, n=8). Exercise training began from 7th day after injury and lasted for 4 weeks. The locomotor function was assessed by Basso-Beattic-Bresnahan(BBB) scale before injury and at the 1st, 2nd, 3rd, 4th and 5th week post injury. The expression of BDNF and TrkB protein in spinal cords were detected by method of immunohistochemistry and Western blot. Results BBB scores in exercise and control groups were higher than that at 1 week and 2 week post injury, and BBB scores in exercise group increased more significantly than that in control group (P<0.05). In immunohistochemistry test positive immunologic reaction to BDNF protein was mainly located in anterior horn of spinal cord, the expression level in exercise group was significantly higher than that in sham-operation group and control group (P<0.05). In immunohistochemistry test positive immunologic reaction to TrkB protein was located in anterior horn and dorsal horn and central canal of spinal cord, the expression level in exercise group was significantly higher than that in sham-operation group and control group (P<0.05). Expression of BDNF and TrkB in exercise group rats after exercise for 4 weeks were significantly increased, compared with control group (P <0.05). Conclusion Exercise training may effectively induce the expression of BDNF and TrkB in spinal cords and promote the recovery of locomotor function of SCI rats.

Key words: exercise training, spinal cord injury, brain-derived neurotrophic factor, tyrosine kinase receptor B