大鼠损伤脊髓BDNF的表达变化

目的探讨大鼠脊髓横断损伤尾端脑源性神经营养因子(BDNF)基因表达变化及其与神经行为学改变的关系。方法成年SD大鼠66只,随机分为假手术组和脊髓全横断(SCT)术后1d、3d、7d、14d、21d、28d组,其中假手术组和SCT术后28d组13只,其余每组8只。假手术组和SCT术后28d组各取5只大鼠于0、7、14、21、28d进行神经功能评分(BBB评分)后,于28d处死大鼠,取脊髓尾端组织进行原位杂交和免疫组化染色及ELISA分析,观察BDNF mRNA和蛋白在脊髓尾端的表达和分布;剩余每组各时间点取8只大鼠脊髓尾端组织用于RT-PCR检测BDNFmRNA含量变化。结果 SCT后大鼠后肢运动功能消失,BBB评分于术后14d至28d增加较前一时间点明显(P<0.05);原位杂交及免疫组化示BDNF mRNA及其免疫产物定位于神经元胞浆和突起;RT-PCR示SCT术后各时点BDNF mRNA表达与假手术组比较无差异(P>0.05),而SCT术后14d时BDNFmRNA水平高于术后1d和3d(P<0.05);ELISA检测发现损伤脊髓28dBDNF含量高于假手术组(P<0.05)。结论 SCT后大鼠后肢运动功能随时间呈现一定可塑性,其机制可能与BDNF表达增加相关。

Implication of BDNF expression in transected spinal cord of rats

Objective To explore the change of brain derived neurotrophic factor（BDNF） expression and its relationship with the neurological behavior after spinal cord transection（SCT） in rats.Methods 66 adult SD rats were assigned randomly to sham operation group and SCT group. Rats in SCT group were subjected T₁0-T₁1 spinal cord transection and allowed to survived 1 d,3 d,7 d,14 d,21 d and 28 d.BBB scores in hindlimbs were observed at 0,7,14,21 and 28 days post operation（dpo）.The BDNF expression was determined by using ELISA（28 d） and RT-PCR（each time point） techniques.The localization of BDNF and its mRNA at sham and 28 d after SCT was also observed by immunohistochemistry and in situ hybridization.Results After SCT,the motor function in hindlimbs disappear immediately.The BBB scores get a gradual recovery from 14 dpo to 28 dpo,when compared with that of former timepoint（P<0.05）.BDNF and its mRNA were located in cytoplasma and neurites. The level of BDNF mRNA（indicated by RT-PCR） was upregulated at 14 days after SCT than that in 1 and 3 dpo（P<0.05）.The contents of BDNF in the injuried spinal cords at 28 dpo were increased than that in the sham operation group（P<0.05）.Conclusion Neuroplasticcity has occurred in rats subjected to SCT,and the mechanism may be involved in the increase of BDNF expression in the spinal cord with the time going.