X线照射治疗脊髓损伤大鼠的效果及其可能机制

Treatment effects of X-ray irradiation on rats with spinal cord injury and its possible mechanism

目的分析X线照射治疗脊髓损伤(SCI)大鼠的效果,并探讨其可能的作用机制。方法将75只雌性SD大鼠随机分为假手术组(Sham组)、SCI组、SCI+2 Gy组、SCI+10 Gy组、SCI+20 Gy组,每组15只。除Sham组外,其他组均采用Allen法建立SCI模型。术后2 h,给予SCI+2 Gy组、SCI+10 Gy组和SCI+20 Gy组大鼠相应剂量的X线单次照射治疗。于术前及术后第1天、第14天,采用巴索-贝蒂-布雷斯纳汉(BBB)量表和斜板试验评估大鼠运动功能的情况;术后第14天,取脊髓组织观察空腔面积比例和尼氏小体所占的面积比例,采用免疫组织化学染色和蛋白免疫印迹法检测髓鞘碱性蛋白(MBP)、肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)、胶质纤维酸性蛋白(GFAP)、波形蛋白(Vimentin)的表达情况。结果(1)与Sham组相比,其他组大鼠术后各时间点的BBB评分、最大倾斜度降低或减小,术后第14天的脊髓空腔面积比例增大,而尼氏小体所占的面积比例降低(均P<0.05);术后第14天,SCI组、SCI+2 Gy组、SCI+20 Gy组、SCI+10 Gy组大鼠的BBB评分和最大倾斜度依次增加,脊髓空腔面积比例依次减小,而尼氏小体所占面积比例依次增加(均P<0.05)。(2)术后第14天,与Sham组相比,其他组大鼠脊髓组织中MBP的相对表达量均降低,TNF-α、IL-1β、GFAP、Vimentin的相对表达量均增加(均P<0.05);SCI组、SCI+2 Gy组、SCI+20 Gy组、SCI+10 Gy组大鼠脊髓组织中MBP相对表达量依次升高、TNF-α、IL-1β、GFAP、Vimentin的相对表达量均依次降低(均P<0.05)。结论X线照射治疗可有效地改善SCI大鼠的神经功能,其机制可能为通过抑制炎症和胶质瘢痕形成为神经元存活和髓鞘再生提供有利的微环境。

Objective To analyze the treatment effects of X-ray irradiation on rats with spinal cord injury(SCI),and to explore its possible mechanism.Methods Seventy-five female SD rats were randomly divided into sham-operation group(Sham group),SCI group,SCI+2 Gy group,SCI+10 Gy group and SCI+20 Gy group,with 15 rats in each group.Except for the Sham group,the models of SCI were established in the other groups using the Allen method.Two hours after the operation,rats in the SCI+2 Gy,SCI+10 Gy,and SCI+20 Gy groups were treated with once X-ray irradiation at corresponding doses.Before the operation,on the first and 14th days after the operation,the Basso-Beattie-Bresnahan(BBB)scale and inclined plane test were used to evaluate the condition of motor function of the rats;on the 14th day after the operation,the spinal cord tissues were harvested to observe the proportions of cavity area and Nissl bodies′area,and immunohistochemical staining and Western blotting assay were employed to detect the expression of myelin basic protein(MBP),tumor necrosis factorα(TNF-α),interleukin 1β(IL-1β),glial fibrillary acidic protein(GFAP),and Vimentin.Results(1)Compared with those in the Sham group,rats in the other groups had decreased BBB scores and maximum slopes at each time point after the operation,increased proportions of the areas of spinal cord cavity on the 14th day after the operation,and reduced proportions of Nissl bodies′areas(all P<0.05);on the 14th day after the operation,rats′BBB score and maximum slope increased,the proportion of the area of spinal cord cavity decreased,and the proportion of Nissl bodies′area rose in the order of the SCI group,the SCI+2 Gy group,the SCI+20 Gy group and the SCI+10 Gy group(all P<0.05).(2)On the 14th day after the operation,as compared with those in the Sham group,rats in the other groups exhibited lower relative expression of MBP in spinal cord tissues,and elevated relative expression of TNF-α,IL-1β,GFAP,and Vimentin(all P<0.05);the relative expression of MBP in spinal cord tissues increased and the relative expression of TNF-α,IL-1β,GFAP,and Vimentin decreased in the order of the SCI group,the SCI+2 Gy group,the SCI+20 Gy group and the SCI+10 Gy group(all P<0.05).Conclusion X-ray irradiation therapy can effectively improve the nerve function of SCI rats,and its mechanism may be providing a favorable microenvironment for the survival of the neurons and remyelination via inhibiting inflammation and glial scar formation.