大鼠慢性马尾神经受压后脊髓内诱导型一氧化氮合酶与神经细胞凋亡的相关性

Correlation between Expression of Inducible Nitric Oxide Synthase and Neural Cell Apoptosis after Chronic Compression of Cauda Equina Nerve in Rats

目的研究大鼠马尾神经慢性受压后诱导型一氧化氮合酶(i NOS)在脊髓内的变化,及其与相应节段脊髓内神经细胞凋亡的相关性。方法将健康成年SD大鼠30只随机分为对照组和实验组。对照组行假手术,仅切除L5椎板,实验组在L4平面置入硅胶片,造成马尾神经单节段受压。实验组分别于建模后第2、4、8、12周后,对照组于第4周,取腰L4前角脊髓组织,切片后进行免疫组织化学方法并结合图像分析技术,检测脊髓内i NOS的表达变化,应用TUNEL法检测凋亡神经细胞,透射电镜观察神经细胞形态学改变。结果对照组脊髓有极少量i NOS表达;实验组造模后第4周有轻度表达,第8、12周i NOS明显高于对照组。对照组脊髓中可见少量神经细胞凋亡,实验组从第4周起可见明显凋亡的神经细胞,且凋亡数量随时间的延长而增多。透射电镜观察发现实验组神经细胞发生凋亡改变。结论大鼠马尾神经慢性受压后,相应节段脊髓神经细胞i NOS表达增加,神经细胞发生凋亡,i NOS与神经细胞凋亡存在正相关。

Objective To study the relationship between the expression of inducible nitric oxide synthase （iNOS） and neural cell apoptosis after chronic cauda equina compression. Methods Totally 30 male adult SD rats were randomly divided into 2 groups as the control group and the experi- mental group. The control group received sham operation with single laminectomy of L5 lumina. In the experimental group, the silicon sheet was in- serted into the spinal canal of L4 to cause single level compression of canda equina. The L4 level of spinal cords were harvested at 2 weeks, 4 weeks, 8 weeks, and 12 weeks after operation in the experimental group, and at 4 weeks in the control group respectively, and then immunohistochemistry and image analysis were performed to observe the expression of iNOS in spinal cord and the TUNEL method was applied to observe cell apoptosis. The morphology of cells was observed by transmission electron microscope. Results There was few amount of iNOS expressed in the control group. The expression of iNOS was slight at 4 weeks in the experimental group and was higher at 8 weeks and 12 weeks compared with the control group. Small amount of neural cell apoptosis was evidenced in the control group, while neuron apoptosis appeared remarkably in the experimental group since 4 weeks and increased with the extension of time. Transmission electron microscopy found apoptosis changes in neurons in the experimental group. Conclusion The expression of iNOS increases in corresponding spinal cords after chronic compression of cuada equine and neural cell apeptosis oc- curs, indicating that iNOS is positively correlated with neural cell apoptosis.