罗格列酮对大鼠脊髓损伤后的保护作用及其机制

Protective effect of rosiglitazone on spinal cord injury of rats and its mechanism

目的:探讨罗格列酮对脊髓损伤后的保护作用以及对表皮生长因子受体(EGFR)磷酸化和胶质瘢痕形成的影响。方法:65只SD大鼠随机分为假手术组、溶媒对照组(1、3、7、14、21 d和28 d)与罗格列酮组(1、3、7、14、21 d和28 d)。溶媒对照组和罗格列酮组进行T10节段半横断(右侧),假手术组只行椎板切除,不损伤脊髓;罗格列酮组在术后5 min、6 h、24 h均以2.5 mg/kg剂量腹腔注射罗格列酮,其他组注射等量的生理盐水。术后行BBB评分。各时间点取材后采用免疫组化法检测脊髓组织过氧化物酶体增殖激活受体γ(PPARγ)、p-EGFR及胶质纤维酸性蛋白(GFAP)的表达,并经Motic Images Advanced 3.2系统处理后对免疫组化阳性区域的平均光密度值进行t检验、F检验。结果:BBB评分显示,罗格列酮治疗后运动功能明显恢复。免疫组化结果及统计学分析显示,脊髓损伤后PPARγ、p-EGFR及GFAP表达增高。罗格列酮组经治疗后PPARγ较溶媒对照组表达明显增多,尤其是7、14 d和28 d(P<0.05);p-EGFR在各个时间点的表达均减少,尤其1、3、7 d差异明显(P<0.05);GFAP随时间增长,呈现先增高后减少的趋势(P<0.05),峰值出现在14 d。结论:罗格列酮能够促进脊髓损伤后PPARγ表达,下调p-EGFR及GFAP表达抑制星形胶质细胞的活性,这些可能是脊髓损伤后运动功能恢复的机制。

Objective： To investigate the protective effect of rosiglitazone （ROS） on spinal cord injury and its influence on epidermal growth factor receptor（EGFR） phosphorylation and glial scar formation. Methods： sixty five SD rats were randomly divided into sham group, solvent control group （1,3,7, 14, 21,28 d） and ROS group （1,3, 7, 14, 21,28 d）. Solvent control group and ROS group received spinal cord hemisection at the T10 （right side）, while the lamina of vertebral arch of sham group was destructed without spinal cord hemisection. Each animal in ROS group was injected with ROS introperitoneally in dose of 2.5 mg/kg at the time of 5 min, 6 h and 24 h after operation. The solvent control group and sham group were injected with equivalent saline. BBB scores were assessed after operation. The spinal cord tissues were processed by immunohistochemistry to detect the expression of PPARγ （peroxisome proliferater actived receptor）, p- EGFR （p-epidermal growth factor） and GFAP （glial fibrillary acidic protein）. The mean optical density of immunohisto- chemistrical positive area was analysed by the method of t-test and F-test after processed by the Motic Images Advanced.Results： BBB scores showed significantly improved motor function with treatment of ROS. Immunohistochemistry results and statistic analysis showed that, after hemisection, the expression level of PPARγ, p-EGFR, and GFAP increased. The expression of PPARγ increased significantly with ROS administration compared with solvent control group, especially at 7, 14 and 28 d （P 〈 0. 05 ）. Expression of p-EGFR decreased at each time point, especially at 1, 3 and 7 d （P 〈 0. 05）. Expression of GFAP increased with time, showing a trend of decrease after 1 d （P 〈 0.05）, and it reached the expression peak at 14 d. Conclusion： ROS upregulates expression of PPARγ, and downregulates that of GFAP and p-EGFR, which inhibits the activation of astrocytes. These might be the mechanisms for motor function recovery of rats after SCI.