镁离子对大鼠弥漫性轴索损伤超微结构的影响

Effect of magnesium on ultrastructural changes after traumatic diffuse axonal injury in rats

目的探讨镁离子(Mg2+)对脑弥漫性轴索损伤(diffuse axonal injury, DAI)脑干超微结构的影响. 方法选健康成年雄性SD大鼠36只,体重350～450 g,将其随机分为实验组、对照组、空白组,每组为12只.采用改良Marmarou模型制作DAI模型,伤后30 min分别给予MgSO4 250 μmol/kg、等渗盐水0.2 ml,伤后24 h处死.用透射电镜分别检测脑干超微结构,并行综合组织损伤评分. 结果伤后24 h, 对照组髓鞘分离,线粒体嵴明显肿胀;实验组未见髓鞘分离,线粒体轻度肿胀.实验组脑干综合组织损伤程度评分明显轻于对照组. 结论 Mg2+可在超微结构水平阻止DAI轴索的继发性损害,对DAI具有一定的保护作用.

Objective To explore the effect of magnesium on ultrastructure of brain stem after diffuse axonal injury (DAI). Methods Twenty-six male Sprague-Dawley rats were divided into two groups randomly, ie, experimental group and control group. The rat brain DAI model was produced by modified Marmarou model. The experimental group was administrated with an intravenous bolus of MgSO_4 (250 μmol/㎏) at the 30th minute after DAI was induced; the control group was given an intravenous bolus of equal volume of normal saline. The animals were sacrificed 24 hours after injury. The changes of ultrastructure of brain stem were detected with transmission electron microscope for a comprehensive evaluation of tissue injury. Results At the 24th hour after injury, transmission electron microscope showed that myelin lamella was not separated and mitochondria swelled up mildly in the experimental group. However, myelin lamella was separated and mitochondria swelled obviously in the control group. The score of general damaged axonal in brain stem in experimental group were less than that in the control group. Conclusion Magnesium can inhibit secondary axonal insult at ultrastructure level and exert certain protective effect on DAI.