大鼠急性脊髓损伤后内质网应激相关蛋白CHOP的表达及其意义

Expression and significance of CHOP related ERS after acute spinal cord injury in rats

目的:探讨内质网应激相关蛋白CHOP在急性脊髓损伤中的表达及其意义。方法:48只健康SD大鼠随机分为实验组与对照组(每组24只),实验组采用Allen法制作急性脊髓损伤模型,对照组只切开椎板不损伤脊髓。分别于伤后3h、1d、3d、7d时(每个时间点6只)应用改良Tarlov评分法评价其神经功能;然后处死动物,取受损节段脊髓行HE染色及免疫组化染色,观察形态学变化和CHOP在脊髓组织中的分布特点;并应用TUNEL方法检测神经细胞凋亡情况。其量的评定借助于IPP(Image-ProPlus6.0)软件,结果分别用累积光密度(integratedopticaldensity,IOD)及平均光密度(meandensity)表示。结果:对照组大鼠均未见明显瘫痪,实验组出现不同程度的下肢功能障碍,对照组各时间点的Tarlov评分均高于实验组(P<0.01)。对照组各时间点未见明显坏死细胞和细胞凋亡,实验组出现不同程度的细胞坏死和凋亡。实验组CHOP表达各时间点均明显高于对照组(P<0.01),实验组内CHOP表达1d增加,3d达到高峰,7d减少。实验组内细胞凋亡1d时增加,3d达到高峰,7d减少,且3h<1d<3d>7d(P<0.01)。CHOP表达与细胞凋亡在时间上具有一致性,相关系数为0.644。结论:急性脊髓损伤能够诱导CHOP表达,CHOP表达的增高可能与内质网应激诱导的神经细胞凋亡有关。

Objective：To investigate the significance and expression of CHOP/GADD153 （C/EBP homologous protein/growth-arrest and DNA damage inducible gcne 153） after acute spinal cord injury and the role of ERS to spinal cord injury.Method：Rat model of ASCI at level of T8-T10 was established using modified Allen＇s method.All rats were randomly divided into two groups：test group experienced SCI while sham group were left as control.The nerve function of spinal cord was evaluated by modified Tarlov score,after that the animals were sacrificed at 3h,24h,3d,7d respectively after injury.The morphologic character and expression of CHOP was detected by immunohistochemistry.Cell apoptosis was examined using the TUNEL assay.The expression of CHOP and apoptosis was quantified by the use of IPP（Image-Pro Plus 6.0）.The resuh was showed as the forms of IOD （integrated optical density） and mean density.Result：Paralysis was evidenced in test group rather than sham group with the Tarlov score in the former much higher than that in the latter at each timepoint （P〈0.01）.However necrostic cells and apoptotic cells were not evidenced significantly in sham group sham rather than in test group at each times-point （P〈0.01）.The expression of CHOP and cell apoptosis in test group both elevated at ld,which peaked at 3d and decreased at 7d after SCI with the same tendency of 3h〈1d〈3d〉7d （P〈0.01）.Cell apoptotic was time-consistent with the expression of CHOP with the correlative coefficieney （Preason＇s） of 0.644.Conclusion：ASCI can induce the expression of CHOP by means of ERS, which is related to the aptoposis of neurocyte.