脉冲电磁场对大鼠骨骼肌急性挫伤后成肌分化因子D表达的促进作用

Effects of pulsed electromagnetic fields on the expression of MyoD after acute skeletal muscle contusion

目的观察脉冲电磁场（PEMFs）对大鼠骨骼肌急性挫伤（ASMC）后组织学及成肌调节因子D（MyoD）表达的影响，并探讨脉冲电磁场在大鼠骨骼肌急性挫伤早期治疗中的应用。方法将42只Sprague-Dawley大鼠随机等分为治疗组（造模＋PEMFs干预）、造模对照组（造模）、空白对照组（不予任何处理），每组大鼠14只。治疗组与造模对照组大鼠均选取大鼠左后肢小腿三头肌，采用金属砝码在PVC管引导下垂直下落建立ASMC模型。治疗组造模成功后即刻予以PEMFs干预1次。每组分别在造模成功后第12小时和第18小时随机处死7只大鼠，取小腿三头肌进行HE染色观察，测定MyoD荧光强度。结果造模对照组在两个时间点均出现胞浆淡染、胞核多形态改变，在治疗组，其程度明显减轻，但较空白对照组严重；治疗组及造模对照组的MyoD荧光强度，第18小时均高于第12小时（P〈0．01），且两组在各时间点的表达均高于空白对照组（P〈0．01），第18小时，治疗组高于造模对照组（P〈0．01）。结论大鼠骨骼肌急性挫伤后早期应用PEMFs，可以在干预后18h出现MyoD的表达上调，这可能是PEMFs促进骨骼肌再生的机理之一。

Objective To observe the effects of pulsed electromagnetic fields （PEMFs） on histological changes and myogenic differentiation factor D （MyoD） expression in rats with acute skeletal muscle contusion （ASMC） , and to explore the effects of PEMF therapy on rats with ASMC in its very early stages. Methods Fortytwo rats were randomly divided into three groups： a treatment group, a control group and a blank control group. ASMC models were established with all the animals in the treatment and control groups. PEMF treatment was administered to the treatment group immediately after the establishment of the ASMC model. Seven rats in each group were sacrificed at the 12th and 18th h after the models were set up. Their triceps surae muscles were sampled and treated with haematoxylin-eosin staining for study using immunofluorescence techniques and a fluorescence microscope. Results In the control group at the 12th h and 18th h, HE staining showed pale cytoplasm and polymorphism in the cell nuclei; in the treatment group these effects were significantly lighter, but in both groups it was more serious than in the blank control group. In the treatment and control groups, the fluorescence intensity of MyoD at the 18th h was higher than at the 12th h, and at each time point in both groups it was higher than in the blank control group. At the 18th h, fluorescence in the treatment group was stronger than in the control group. Conclusion MyoD expression in rats with ASMC is upregulated by the 18th h after early PEMF treatment. This might be one of the mechanisms accelerating the regeneration of skeletal muscles after trauma.