脊髓损伤后细胞凋亡及iNOS的表达

Apoptosis and expression of iNOS after spinal cord injury in rats

目的研究大鼠脊髓损伤后细胞凋亡的特点与诱生型一氧化氮合酶 (induciblenitricoxidesynthase,iNOS)的表达规律以及两者之间的关系。方法成年SD大鼠随机分为 3组 ,分别造成轻、中、重度脊髓急性损伤模型 ,于损伤后不同时间点 (4h、8h、1d、3d、7d、1 4d、2 1d)处死。用HE染色观察损伤脊髓组织病理变化 ,用免疫组化染色检测iNOS、Bax阳性细胞 ,TUNEL法标记凋亡细胞。结果HE染色镜检发现脊髓组织病理学改变随着损伤程度的增加而加重。免疫组化结果显示正常对照组及单纯椎板切除组神经元、神经胶质细胞、室管膜细胞、血管内皮细胞极少量表达iNOS ;损伤后 8小时上述细胞iNOS表达增加 ,7天达高峰 ,1 4天仍较明显 ,2 1天降低。Bax表达及TUNEL标记阳性细胞的时间分布特点与iNOS相似 ,7天达高峰 ,阳性细胞以白质中胶质细胞为主。iNOS表达与脊髓损伤程度及神经细胞凋亡指数间存在正相关 (r=0 41 4 ,P <0 0 1 ;r=0 854 ,P <0 0 1 )。结论大鼠脊髓损伤后iNOS和Bax表达增强 ,凋亡神经细胞大量出现。

ObjectiveTo study the characteristic of apoptosis and the expression of inducible nitric oxide synthase(iNOS),as well as relation between them after spinal cord injury (SCI) in rats.Methods84 adult SD rats were randomly divided into three groups,and made into mild,moderate and severe acute SCI models.The rats were killed at 4h,8h,1d,3d,7d,14d and 21d after surgery.The histopathology changes in spinal cord tissue were observed with HE staining microscopic examination.The expression of iNOS was determined by immunohistochemistry and the apoptosis was labeled by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling(TUNEL).ResultsThe histopathology changes in spinal cord tissue deteriorated with increasing in injury degree.A little iNOS immunoreactivity (iNOS IR) was detected in nerve cells,gliocytes,ependymocytes and blood vessel endotheliocytes of normal and vertebra shelf operated controls,increasing at 8 h, and in flood tide in 7 d. The expression of Bax and the rates of TUNEL positive cells were similar with that of iNOS after SCI. There was positive correlation between expression of iNOS and degree of primary SCI ,apoptosis index( r =0 414, P <0 01; r =0 854, P <0 01).Conclusions Expression of iNOS and Bax increase and a large number of TUNEL positive cells present after SCI in rats. There is positive correlation between expression of iNOS and degree of primary SCI,apoptosis index.