大鼠脊髓打击伤模型的建立及病理观察

目的 观察改良大鼠脊髓打击伤模型的病理变化,评价该模型的稳定性、重复性和一致性. 方法 应用改良重物坠落打击装置建立大鼠脊髓中、重度损伤模型,通过BBB评分、神经电生理监测、免疫组化及光电镜技术观察脊髓损伤(SCI)后两组大鼠功能及病理变化特点,以评价本实验模型的重复性及与损伤程度相关的一致性. 结果 脊髓损伤后两组大鼠的后肢运动功能均有不同程度恢复,运动和感觉诱发电位提示神经信号传导功能亦逐渐恢复,但中度损伤大鼠恢复明显较重度损伤大鼠好,组织病理及免疫组化观察显示脊髓损伤后有胶质瘢痕及囊腔形成,但重度损伤组的组织损伤程度较中度组重,且残留正常组织较少,电镜下观察显示脊髓损伤后损伤部位可见明显出血、水肿,中性粒细胞浸润,胶质细胞染色质边集.脊髓损伤后2周可见线粒体空泡化,轴突变性,周围水肿.脊髓损伤后8周可见髓鞘变性,胶原原纤维沉积. 结论 本实验模型能将不同打击力度造成的损伤区分开,且和行为学、神经电生理、病理学等结果吻合,说明此模型具有良好的稳定性、重复性和一致性.胶质瘢痕及囊腔的形成是脊髓损伤的标志性病理变化,GFAP或Vimentin染色可作为判断其界限的标志性分子.

Establishment of rat model of impact spinal cord injury and pathological observations

Objective To establish rat model of impact spinal cord injury, observe the pathological changes of the model and assess its stability, reproducibility and consistency. Methods Moderate and severe spinal cord injury (SCI) models were established by using modified weight drop device. The pathological and functional changes after SCI were observed by means of BBB scoring, electrophysiology,immunohistochemistry and electronic microscopy so as to estimate the reproducibility of rat models and their consistency with severity of SCI. Results Locomotion and nerve impulse transduction along the spinal cord measured by motorial and sensory evoked potentials recovered gradually over time after SCI.However, the recovery rate of moderate SCI group was better than that of severe SCI group. Histological and immunohistochemical experiments showed that the glial scar as well as cavity were formed after SCI.Whereas, compared with moderate SCI group, the injury of severe SCI group was severer, with less spared tissue. Electronic microscopic observation displayed that hemorrhage, edema, neutrophilic granulocytic infiltration and chromatin margination of glia arose at day 1 after SCI. Vacuolization of mitochondria, degeneration of axon with edema could be seen at 2 weeks after injury. Degeneration of myelin and deposition of collagen fibril emerged at 8 weeks postinjury. Conclusions The rat models of impact SCI established in this study can distinguish the graded injury, and significantly correlate with the behavioral,electrophysiological and pathological outcomes, which indicates that the models possess good stability, reproducibility and consistency. Glial scar with cavity marked by GFAP or Vimentin is the pathological hallmark after SCI, and thereby GFAP or Vimentin can be used as a marker for demarcate the border of glial scar.