Abstract: Objective To observe the influence of brain-derived neurotrophic factor on demyelination of myelinated nerve fibers after compressed spinal cord injury, so as to build up the experimental basis for BDNF’s repairing function on nerve fibers demyelination. Methods rats were divided into groups averagely： normal group, sham group, compressed group and decompressed group. The CSCI mode was established by a custom-made compressor. For the compress group, the rats were subjected to spinal cord compression for 12 h; for the decompress group, only 1h; while the sham group just exposed the spinal cord .The changes of nerve fibers were observed on day 1,3and7 after CSCI by osmic acid staining. The expression of BDNF and MBP were detected by Western blot and double-labelling immunofluorescence.Result axonal demyelination occurred in both compress and decompress group. Myelin sheath became swelling, degenerating and breaking down with the flowing of time. The expression of BDNF and MBP decreased gradually as the time went by(p<0.05). But compared to the compress group, the demyelinating in the decompress group was less serious and the reduction both in MBP and BDNF was less and slower(p<0.05).Conclusion early decompression can reduce demyelination which may be related with the expression of BDNF in CSCI.

Key words: 【Key words】： Brain-derived neurotrophic factor , Compressed spinal cord injury, Demyelination, myelin basic protein, Rats