减压对大鼠脊髓压迫性损伤后脱髓鞘病变和BDNF表达的影响

Effect of decompressed on demyelination and BDNF expression in spinal cord of rats after compressed spinal cord injury

目的观察脑源性神经生长因子(BDNF)对脊髓压迫性损伤(CSCI)后有髓神经纤维脱髓鞘病变的影响,为阐明BDNF对神经纤维脱髓鞘病变修复提供实验基础。方法将大鼠均分成4组:正常组、假手术组、压迫组和减压组。用自行设计的压迫器制作大鼠脊髓压迫模型。压迫组作脊髓压迫12 h,减压组作脊髓压迫1 h,假手术组仅作脊髓显露,不作压迫。用锇酸染色观察CSCI后1、3和7 d有髓神经纤维变化情况;Western blot和免疫荧光双标检测BDNF和髓鞘碱性蛋白(MBP)的表达。结果压迫组和减压组都出现脱髓鞘病变,并随着时间的延长,髓鞘逐渐水肿、变性、MBP崩解。BDNF表达量在CSCI后随时间延长也逐渐降低(P<0.05),但与压迫组相比较,减压组脱髓鞘病变较轻且MBP和BDNF降低幅度小而缓慢(P<0.05)。结论 CSCI后尽早减压可减轻脱髓鞘的发生,且可能与BDNF的表达有关。

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 four groups randomly： 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 1 h ; 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 was detected by Western blot and double-labelling immunofluorescence. Results 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 with time （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）. Conclusions Early decompression can reduce demyelination which may be related with the expression of BDNF in CSCI.