| Partâ… CORRELATION STUDY OF DEMYELINATION AND EXPRESSION OF BDNF AFTER DECOMPRESSION OF COMPRESSED SPINAL CORD INJURYObjective:To observe the expression of brain-derived neurotrophic factor(BDNF) and its effect on demyelination of myelinated nerve fibers after compressed spinal cord injury(CSCI), for providing experimental basis and clarifying the protective effect of BDNF on myelin sheath.Methods: Total of 80 adult male Sprague-Dawley rats were randomly divided into four groups: normal group, sham group and decompress group,while the decompress group further divided into two subgroups, decompress group 1 and 2, each group 20 rats. The self-designed compression device were adapted to establish the CSCI model of rats.For the decompress group 1 and 2, the rats were subjected to spinal cord compression for 1h and12 h respectively; the sham group just exposed the spinal cord while the normal group received no treatment. The Basso, Beattie and Bresnahan(BBB) score was used to measure neurological changes and myelin of myelinated nerve fibers were observed by osmic acid staining on day 1,3and7 after CSCI. The expression of BDNF and MBP were detected by Western blot and double-labelling immunofluorescence.Results: The BBB scores of normal and sham group were 21 and basically normal; the myelin sheath of nerve fibers were integrity with no reducing of the number. While in both decompress group, BBB scores were decreased with demyelination and myelin sheath became swelling, degenerating and breaking down with time. When compared with the decompress group 2, BBB Scores of group 1 reduced slowly with less demyelination and higher res idual nerve fibers(P <0.05). Western blot and immunofluorescence double labeling showed that the expression of BDNF and MBP decreased gradually as time went by, and the reduction of BDNF and MBP were s ignificantly lower in the decompress group 1than the group 2(p<0.05)Conclusion: Demyelination occurs after CSCI, and the severity was negatively correlated with BDNF, while decompressing as soon as possible after CSCI can promote expression of BNDF and enhance residual nerve fibers. This implies that BDNF has a protective effect on demyelination after CSCIPart â…¡ TO EXPLORE THE MECHANISM OF BDNF EXPRESSION AFTER COMPRESSED SPINAL CORD INJURYObjective:To observe the expression of brain-derived neurotrophic factor(BDNF) in anterior part(T11), midpiece(T12) and posterior part(L1) of compressed spinal cord, for explore the mechanism of BDNF expression after CSCI.Methods: 60 adult male SD rats were divided into 3 groups randomly:model group, sham group and normal group,each group 20 rats. Model making method were the same as the first part. The normal group received no treatment;the sham group just exposed the spinal cord, while model group received spinal cord compression for 24 h. The anterior, the midpiece and the posterior part of spinal cord after CSCI for 24 h were collected respectively. The changes of myelinated nerve fibers was observed by osmic acid staining and LFB(luxol fast blue); western-blot were used to identify the expression changes of BDNF and MBP(myelin basic protein).Results:For osmic acid staining and LFB, there was no significant difference in the number of myelinated nerve fibers in the normal and the sham group. The myelinated nerve fibers also has no significant change in the anterior part of compression between the model and the sham group after CSCI for 24h(P>0.05). While the number of myelinated nerve fibers of the midpiece(T12) and the posterior part(L1) in the model group is decreased when compared with the corresponding part of the sham group(P<0.05). Moreover, the reduction of residual nerve fibers in the midpiece were more serious than the posterior part in the model group(P<0.05). Western blot showed that:compared with the sham group,the expression of BDNF in the anterior part of the model group increased(P<0.05), but the expression of MBP was normal. For model group, the expression of MBP and BDNF decreased in midpiece and the posterior part(P<0.05), and the midpiece reduced more obviously.Conclusion: There was a positive correlation between the expression of BNDF and demyelinating after CSCI. Increased BDNF expression has a protective effect on demyelination, while decreased expression of it lead to the loss of myelin sheath. In the model group, decreased expression of BDNF in the midpiece and the posterior part, and the increased expression of BDNF in the anterior part of compression may related to hindering the transport of BDNF after CSCI. |
