一氧化氮和超氧化物歧化酶在Duchenne肌营养不良患儿肌肉组织中的表达

Expression of Nitric Oxide and Superoxide Dismutase in Skeletal Muscle of Children with Duchenne Muscular Dystrophy Patients

目的观察一氧化氮(NO)和超氧化物歧化酶(SOD)在Duchenne肌营养不良(DMD)肌肉组织中的表达,探讨DMD肌肉组织的慢性炎症、变性和坏死的病理形成以及肌疲劳的发生机制。方法选择40例1.5～12.0岁的DMD患儿(DMD组)和7例非神经肌肉疾病骨折患儿(对照组)(1.0～12.0岁),利用免疫组织化学方法对其骨骼肌纤维膜上的神经源性一氧化氮合酶(nNOS)表达进行测定;通过腺苷三磷酸环化酶(ATPase)和琥珀酸脱氢酶(SDH)染色对骨骼肌肌纤维进行分型,并通过显微图像系统对单一肌纤维SDH活性进行定量分析;利用生物化学方法对骨骼肌中总NO水平和总SOD活性进行测定。结果与对照组比较,nNOS表达在DMD患儿的肌细胞膜上均呈现缺失现象;SDH活性在单一肌纤维中均呈现低下趋势;NO总水平和总SOD活性在肌肉组织中均呈现较高的表达。结论过量的NO自由基不仅是导致DMD患儿肌肉组织病理形成的原因之一,而且抑制线粒体呼吸链氧化酶、降低骨骼肌有氧代谢能力致使DMD患儿肌肉疲劳的发生。

Objective To study the correlation between Duchenne muscular dystrophy（DMD） and the metabolism of nitric oxide（NO） and superoxide dismutase（SOD）,investigate the mechanism of muscle chronic inflammation,pathogenesis of degeneration and necrosis and muscular fatigue,by observing the expression of NO and SOD in skeletal muscle of DMD patients.Methods The skeletal muscle samples were collected from 40 cases of diagnosed DMD（DMD group,aged 1.5-12.0 years） and 7 controls（control group,aged 1.0-12.0 years）.The expression of neuronal nitric oxide synthase（nNOS） at the sarcolemma was assayed by immunohistochemistry.Fibre types were classified based on histochemical staining for myosin ATPase and succinate dehydrogenase（SDH） The value of SDH activity of single muscle fibre was determined using the image processing system.SOD activity and total concentration of NO in the skeletal muscle were tested by biochemistry methods.Results Compared with control group,the expression of nNOS was lacked in the sarcolemma,and SDH activity in single muscle fiber was tended to reduce in DMD group.The total contents of NO and SOD activity were increased in DMD.Conclusions NO radical not only causes muscle pathogenesis,but also inhibits the oxidation of mitochondrial respiratory chain enzyme,reduces the aerobic capacity of skeletal muscle which result in muscular fatigue in DMD patients.