大鼠脊髓损伤后坐骨神经电生理学以及损伤脊髓GAP-43蛋白表达的变化

目的：研究大鼠脊髓损伤后不同时间点坐骨神经兴奋阈值、动作电位（AP）幅度和传导速度，以及损伤脊髓GAP-43蛋白表达的改变。方法：采用改良的Allen′s重物坠落致大鼠脊髓损伤实验模型、电生理学和免疫组织化学染色。结果：大鼠SCI后1、3、7d时，坐骨神经兴奋阈值升高，AP幅度和传导速度降低，呈时间依赖性改变；SCI后14d，AP产生阈值、幅度和传导速度较SCI第7d有所恢复。正常大鼠脊髓灰质神经元的胞浆和轴突中有少量GAP-43蛋白表达；SCI后第1、3、5、7d时损伤脊髓周围区灰质GAP-43蛋白表达逐渐增强；在SCI后第14d其阳性表达开始减弱。结论：大鼠SCI后能够导致坐骨神经电生理学兴奋性和传导性的降低，以及神经结构重构蛋白GAP-43表达增加。

Changes of electrophysiology of the sciatic nerve and expression of GAP-43 protein in injured spinal cord tissue of rats

Objective: To investigate the changes of threshold,amplitude and conduction velocity of the action potential(AP) in the sciatic nerve and the expression of GAP-43 protein in rats with spinal cord injury(SCI).Methods: Electrophysiological and immunohistochemistry techniques were used in experimental rats that were induced by the Allen's spinal cord weight-drop-injury method.Results: The increase of threshold, the decrease of amplitude and conduction velocity of AP in the sciatic nerve showed a time-dependent manner at 1 d,3 d and 7 d following SCI.However,the above changes attenuated at 14 d following SCI.Expression of GAP-43 proteins progressively increased at 1 d,3 d,and 7 d following SCI,and reached a peak at the 7th d.Conclusion: The excitability and conductibility of the sciatic nerve degrade and the expression of GAP-43 protein increases following SCI in rats.