Objective: Glucocorticoids (GCs) can induce oxidative damage in skeletal muscles. The purpose of this study was to demonstrate a high caloric (HC) diet rich in soy oil would change the oxidative stress induced by a GC.

Methods: The effect of dexamethasone (DEX) and HC diet on oxidative stress in plasma, skeletal muscles (M. pectoralis major, PM; M. biceps femoris, BF), and mitochondria were determined. The biomarkers of oxidative damage and antioxidative enzyme activity were determined. The fatty acid profile of muscles and the activities of complex I and II in mitochondria were measured.

Results: The results showed that DEX increased the concentrations of oxidative damage markers in plasma, muscles, and mitochondria. The activity of complex I was significantly suppressed by DEX. DEX-chickens had higher proportions of polyunsaturated fatty acids and lower proportions of monounsaturated fatty acids in the PM. A HC diet decreased the levels of oxidative damage biomarkers in plasma, muscles, and mitochondria. The interaction between DEX and diet suppressed the activities of complex I and II in HC-chickens.

Discussion: Oxidative damage in skeletal muscles and mitochondria was the result of GC-induced suppression of the activity of mitochondrial complex I. A HC diet improved the antioxidative capacity and reduced the oxidative damage induced by the GC.

目的：糖皮质激素（GCs）可以诱导骨骼肌的氧化损伤。这项研究的目的是证明富含豆油的高热量（HC）饮食会改变GC诱导的氧化应激。

方法：测定地塞米松（DEX）和HC饮食对血浆，骨骼肌（M. pectoralis major，PM; M. biceps femoris，BF）和线粒体氧化应激的影响。确定了氧化损伤和抗氧化酶活性的生物标志物。测量了线粒体中肌肉的脂肪酸分布以及复合物I和II的活性。

结果：结果表明，DEX增加了血浆，肌肉和线粒体中氧化损伤标记物的浓度。复合物I的活性被DEX显着抑制。在PM中，DEX鸡的多不饱和脂肪酸比例较高，而单不饱和脂肪酸比例较低。HC饮食降低了血浆，肌肉和线粒体中氧化损伤生物标志物的水平。DEX与饮食之间的相互作用抑制了HC鸡体内复合物I和II的活性。

讨论：骨骼肌和线粒体的氧化损伤是GC诱导的线粒体复合体I活性抑制的结果。HC饮食可提高抗氧化能力并减少GC诱导的氧化损伤。