大鼠急性脊髓损伤后神经细胞凋亡与血管内皮细胞的关系

Relationship between neuron apoptosis and vascular endothelial cells after acute spinal cord injury in rats

目的:观察大鼠急性脊髓损伤后凋亡相关蛋白Bax和Bcl-2在邻近节段血管内皮细胞中的表达。探究脊髓继发性损伤中神经细胞凋亡的原因。方法:成年Wistar大鼠40只,随机分为正常对照组,假手术组及脊髓压迫组。于手术后6,24,72h,7,14,28d取以损伤部位为起点头侧端脊髓1.5cm,采用电镜观察超微结构变化;以免疫组织化学技术检测Bax及Bcl-2的表达;以TUNEL法检测细胞的凋亡。结果:正常组及假手术组Bax和Bcl-2在血管内皮细胞中只有少量表达,压迫组于伤后6h出现Bax在血管内皮细胞中的强阳性表达,伤后3d达到高峰,一两周下降,4周时只有少数阳性细胞。电镜观察,内皮细胞有不同程度的细胞膜起泡,染色体边集,细胞凋亡。结论:在急性脊髓损伤后的继发损伤过程中,神经细胞的凋亡可能是血管内皮细胞损伤的结果。

AIM:To observe the expression of apoptosis related protein Bax and Bcl 2 in vascular endothelial cells(VECs) of the adjacent segment after spinal cord injury so as to determine the cause of neuron apoptosis in the secondary lesion period after spinal cord injury. METHODS:Forty adult Wistar rats were randomly divided into three groups:control group,laminectomy group and spinal cord compression groups.The rats were killed at 6,24,72 hours,7,14 and 28 days after injury.1.5 cm from the injured site lateral spinal segment was taken out and cut.The changes of ultrastructure were observed under the electron microscope,the expressions of Bax and Bcl a were detected with immunohistochemical staining,and the neuron apoptosis was studied by means of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling(TUNEL). RESULTS:Few expressions of Bax and Bcl 2 were present in vascular endothelial cells in the control and laminectomy groups.In the compression groups,Bax immunoreactivity was found with high expression at 6 hours,reached the peak at 72 hours and began to decrease after 7-14 days;Only a few positive VECs were found at 28 days.Different degrees of protuberance of cell membrane,conglomeration of chromosome on the edge and many apoptotic cells of VECs were detected under the electron microscope. CONCLUSION:In the secondary lesion period after spinal cord injury,the neuron apoptosis may be a consequence of damage to the vascular endothelial cells.