脉冲电磁场对大鼠坐骨神经损伤后转化生长因子β1表达的影响

The effect of pulsed electromagnetic fields on the expression of transforming growth factor beta-1 after sciatic nerve injury

目的观察脉冲电磁场（PEMFs）对大鼠坐骨神经损伤后转化生长因子-β1（TGF—β1）表达的影响，探讨PEMFs对周围神经可能的作用机制。方法将48只SD大鼠按随机数字表法分成治疗组、模型组、对照组，每组16只，治疗组和模型组大鼠按文献方法钳夹坐骨神经制成坐骨神经损伤模型。造模成功后，治疗组予以9mT、14HzPEMFs治疗，模型组予以磁感应强度为0的PEMFs治疗，对照组不给予任何干预，保持同样饲养条件至实验结束。根据实验动物处死取材时间点的不同，3组再随机分为治疗1、3、7和14d后共4个亚组，各4只大鼠。于治疗1、3、7和14d分别采用苏木精-伊红（HE）染色法光镜下观察3组大鼠坐骨神经组织学改变，应用免疫组织化学法对损伤后大鼠坐骨神经TGF—β1的表达进行分析。结果治疗1、3、7和14d后，对照组组织学改变与正常坐骨神经类似；治疗1d和3d后，治疗组组织学改变与模型组类似，但治疗7d和14d后，治疗组轴索和髓鞘变性明显重于模型组。免疫组织化学检测发现，治疗后各时间点模型组和治疗组TGF—β1表达的平均积分光密度均显著高于对照组，组间差异均有统计学意义（P〈0．01）。治疗1d后，治疗组TGF—β1表达的平均积分光密度与模型组比较，差异无统计学意义（P〉0．05），治疗3、7和14d后，治疗组TGF—β1表达的平均积分光密度均显著高于模型组，差异有统计学意义（P〈0．01）。结论PEMFs可加速大鼠坐骨神经损伤后的Walierian变性进程，促进大鼠坐骨神经损伤后TGF—β1的表达。

Objective To observe any effects of pulsed electromagnetic fields （PEMFs） on the expression of transforming growth factor beta-1 （TGF-β1） after sciatic nerve injury and to investigate the possible mechanism of any regeneration of the injured sciatic nerve. Methods Forty-eight SD rats were randomly divided into a PEMF treatment group, a model group and a normal control group with 16 rats in each group. The three groups were then sub-divided into 1 day, 3 day, 7 day and 14 day subgroups. The rats of the model and treatment groups were clamped to produce a sciatic nerve injury model. The treatment sub groups were exposed to a 9 mT PEMF at 14 Hz for 2 hours once daily for 1, 3, 7 and 14 days, respectively. The model group was given sham exposure and the normal control group was reared conventionally and not given any special treatment. The histological changes in the rats＇ sciatic nerves were observed under a light microscope after hematoxylin-eosin staining. Expression of TGF-β1 was detected by immunohistochemieal methods. Results After 7 and 14 days of treatment, Wallerian degeneration of the sciatic nerve in the treatment group was more obvious than in the model group. The expression of TGF-β1 increased during the treatment process and reached a maximum at the 14th day after nerve injury. The expression of TGF-β1 had increased significantly in the model and treatment groups compared with the control group at all observation time points. At the 3rd, 7th and 14th day after the operation, the expression of TGF-β1 in the treatment group was significantly higher than that in the model group. Conclusion PEMFs can accelerate Wallerian degeneration of peripheral nerves and can up-regulate the expression of TGF-β1 after sciatic nerve injury, at least in rats.