类固醇肌病大鼠模型的建立及其骨骼肌病变的形态学研究

目的探讨不同剂量皮质类固醇激素以及合成代谢类激素对大鼠骨骼肌的影响。方法用不同剂量地塞米松(dexamethasone,DX)，分别为5mg/kg腹腔注射，每日1次，连用14d和10、20、40、60、90mg/kg腹腔注射，每日1次，连用5d诱导类固醇肌病(steroidmyopathy,SM)的大鼠模型，观察其骨骼肌的病理改变；观察苯丙酸诺龙(NPP)对类固醇肌病的预防效果。结果DX5mg/kg腹腔注射，每日一次连续3天即足以造成大鼠的实验性SM模型，随剂量和疗程的增加，肌肉病变加重；病肌显示肌纤维萎缩和结构破坏，以Ⅱ型纤维为主，Ⅰ型纤维亦可受累，但程度较轻；Ⅰ型肌纤维在DX40、90mg/kg组中比例增高；NPP与DX5mg/kg同步使用未能防止SM的发生，但减轻了肌纤维的坏变程度。结论大鼠实验性SM模型的病肌以肌纤维萎缩为主，伴纤维结构破坏，病变随激素剂量和疗程的递增而加剧；Ⅰ型和Ⅱ型肌纤维均可受累；合成代谢类激素不能防止SM的发生。

Foundation of rat steroid myopathy model and its myopathological study.

Objective 　To investigate the effects of the different dosage of dexamethasone(DX) on the rats skeletal muscle. Methods　We induced steroid myopathy in Wister rats with DX 5 mg/kg i.p. qd×14 d and DX 10, 20, 40, 60, 90 mg/kg i.p. qd×5 d respectively, and observed the pathological changes and the preventive effect of Nandrolone Phenylpropionate (NPP) to this animal model. Results　We found that DX 5 mg/kg i.p. qd×3 d was adequate to induce experimental steroid myopathy in rats. Increase in dosage and duration of glucocorticoid treatment was associated with more severs muscle lesion. The myopathological changes included muscle fibers atrophy and structural damage. Both type Ⅰ and type Ⅱ fiber were affected, but type Ⅱ fiber was affected predominantly. The type Ⅰ fiber quantities were more in DX40, 90 mg/kg group. NPP could not prevent onset of experimental steroid myopathy in rat, but attenuated the muscle fiber necrosis. Conclusions　The myopathological changes in rat steroid myopathy model included muscle fiber atrophy and structural damage, which were more severe with increaseing dosage and duration of glucocorticoid treatment. Both type Ⅰ and type Ⅱ fiber were affected. NPP could not prevent onset of experimental steroid myopathy in rat.