急性重度狗马尾束缢和鞘内注射脑源性神经生长因子对背根神经节的影响

目的设计下腰骶部背根神经节（dorsal root ganglion，DRG）中央突束缢的多重狗马尾束缢模型并致马尾综合征的实验研究，分析鞘内注射可生物降解的脑源性神经生长因子（brain-derived neurotrophic factor，BDNF）在DRG内感觉神经元损伤中的修复作用。方法成年雄性杂种犬（n=18）随机均分成I组（假手术组）、Ⅱ组（对照组）和Ⅲ组（实验组）。Ⅱ组和Ⅲ组动物行多重马尾束缢（multiple cauda equina constrictions，MCEC）48h后解除马尾压缢，同时Ⅲ组鞘内注射可生物降解（PLGA）的纳米微球BDNF（15mg，内含有活性BDNF2．5mg）。术后1周、2周和4周分别取相应DRG行HE染色及BDNF的免疫组化分析，并行神经功能评估和半定量评分。结果MCEC48h后持续观察4周，相比较Ⅱ组、Ⅲ组相应DRG神经元群体内BDNF免疫反应性更强且其神经功能评估、半定量评分改善更明显（P〈0．05）。，结论鞘内注射持续缓慢释放的BDNF纳米粒，在治疗急性重度马尾综合征的狗模型中疗效明显。

Influence on dorsal root ganglion after acute and severe cauda equina constrictions and intrathecal injection of brain-derived neurotrophic factor in experimental dogs

Objective To analyze the repair effect of intrathecal injecting brain-derived neurotrophic factor （BDNF） with encapsulated hiodegradable PLA-PEG copolymer nanospheres for the injured sensory neurons of dorsal root ganglion （DRG）. The experimental constriction injury of the lumbosacral central processes of DRG neurons resulting in the cauda equina synchome （CES） was studied in dogs. Methods Adult mongrel dogs （ n = 18 ） of male were randomly divided into 3 groups （ n =6, respectively） ： group Ⅰ, exposnred only; groups Ⅱ and Ⅲ, performed multiple cauda equina constrictions （MCEC） and removed tightened constrictions after 48 h, and experimental dogs of group m were intrathecally injected with BDNF encapsulated biodegradable PLA-PEG copolymer nanospheres （15 rag, containing 2.5 mg of active BDNF） at the same time. The corresponding level of DRG cells （ L7 ） after 1, 2 and 4 weeks were analyzed using the irmnunohistochemistry and histopathologic methods, and neurological functional assessment and semiquantitative scoring of paraffin sections were performed. Results Continuing observation for 4 weeks, immunohistochemical studies in group m showed a significant innnunoreactivity of BDNF in neuron pool of the corresponding lumbar （ L7 ） DRG and their neurological function and semiquantitative scoring had a significant improvement when compared with the groups Ⅱ （ P 〈 0. 05 ）. Conclusion Intrathecal injection of BDNF with persistent and slow-moving copolymer nanoparticies had obvious therapeutic effect in experimantal dogs of acute and severe cauda equina syndrome.