褪黑素对大鼠急性脊髓损伤保护作用的实验研究

Experimental study of Protective effect of melatonin in the acute spinal cord injury in rats

目的评估褪黑素对SD大鼠急性脊髓损伤的保护作用,通过分析胶质纤维酸性蛋白(glial fibrillaryacid protein,GFAP)及诱导型一氧化氮合酶-1(iNOS-1)在损伤脊髓组织中的表达情况来说明褪黑素保护作用的部分机制。方法将72只大鼠随机分为褪黑素组、甲强龙组、打击对照组和无水乙醇组,以T9为中心,采用改良Allen’s脊髓打击技术,制作急性脊髓损伤模型;损伤后分别注射褪黑素、甲强龙、生理盐水及无水乙醇,分别在2、24和72 h处死取材,应用HE染色、免疫组织化学对脊髓组织进行标记。结果在损伤后,GFAP及iNOS-1的表达在各组均呈逐渐增高趋势,褪黑素组与甲强龙组均较打击对照组表达降低,无水乙醇组与打击对照组无明显差别。结论褪黑素对脊髓损伤具有明显的保护性治疗作用,其保护作用可能是通过抑制GFAP和iNOS-1的表达来实现的,且与甲强龙比较差异无统计学意义。

[Objective] To investigate whether melatonin could protect acute spinal cord injury and further explore its molecular mechanism. [Methods] The 72 SD rats were randomly allocated into four groups： melatonin group, methylprednisolone group, trauma group and vehicle-treated group. Trauma was established by Allen＇s method at the level of T9 with a moderate degree of damage. Melatonin, methylprednisolone, saline or vehicle was administered intraperitoneally immediately after rats after surgery. The spinal cords of rats were isolated at 2, 24, 72 hours post trauma. Sections from all groups were used for hematoxylin and eosin staining, immunohistoehemical staining of GFAP and iNOS-1, and electron microscopy assay. [Results] Significant protection was observed in both the methylprednisolone and melatonin administration groups. GFAP and iNOS-1 expressions were significantly downregulated in methylprednisolone and melatonin groups compared to saline and vehicle-treated groups. No difference in protection and GFAP and iNOS-1 expression were observed between methylprednisolone and melatonin group; [Conclusion] Melatonin shows a significant protective effect on the injured spinal cord though inhibition of GFAP and iNOS-1 expression.