Univ. of Adelaide, SA, Australia.
Am J Physiol Endocrinol Metab. 2010 Apr;298(4):E779-86. doi: 10.1152/ajpendo.00356.2009. Epub 2010 Jan 19.
A high-saturated-fat diet (HFD) induces obesity and insulin resistance (IR). IR has been linked to alterations and increased saturation in the phospholipid composition of skeletal muscles. We aimed to determine whether HFD feeding affects fatty acid (FA) membrane profile in a muscle fiber type-specific manner. We measured phospholipid FAs and expression of FA synthesis genes in oxidative soleus (SOL) and glycolytic extensor digitorum longus (EDL) muscles from rats fed either standard chow (standard laboratory diet, SLD) or a HFD. The HFD increased fat mass, plasma insulin, and leptin levels. Compared with EDL, SOL muscles preferentially accumulated C18 over C16 FAs and n-6 over n-3 polyunsaturated FAs (PUFAs) on either diet. With the HFD, SOL muscles contained more n-9 monounsaturated FAs (MUFAs) and n-6 PUFAs and less n-7 MUFAs and n-3 PUFAs than EDL muscles and had lower unsaturation index, a pattern known to be associated with IR. Stearoyl-CoA desaturase-1 expression was approximately 13-fold greater in EDL than in SOL muscles but did not change with the HFD in either muscle. The expression of Elongase-5 was higher, and that of Elongase-6 (Elovl6) was lower in EDL compared with SOL muscles with both diets. In EDL muscles, the expression of Elovl6 was lower in the HFD than in the SLD. The pattern of FA uptake, expression, and diet-induced changes in FA desaturating and elongating enzymes maintained higher FA unsaturation in EDL muscles. Accordingly, the fiber type composition of skeletal muscles and their distribution may be important in the development and progression of obesity and IR.
高脂肪饮食（HFD）可导致肥胖和胰岛素抵抗（IR）。IR 与骨骼肌磷脂组成的改变和饱和度增加有关。我们旨在确定 HFD 喂养是否以肌肉纤维类型特异性的方式影响脂肪酸（FA）膜谱。我们测量了接受标准饮食（标准实验室饮食，SLD）或 HFD 喂养的大鼠的氧化比目鱼肌（SOL）和糖酵解伸趾长肌（EDL）肌肉中的磷脂 FA 和 FA 合成基因的表达。HFD 增加了脂肪质量、血浆胰岛素和瘦素水平。与 EDL 相比，SOL 肌肉在两种饮食中优先积累 C18 而非 C16 FA 和 n-6 而非 n-3 多不饱和脂肪酸（PUFA）。与 EDL 肌肉相比，HFD 喂养的 SOL 肌肉含有更多的 n-9 单不饱和脂肪酸（MUFA）和 n-6 PUFA，以及更少的 n-7 MUFA 和 n-3 PUFA，且不饱和指数较低，这种模式与 IR 有关。硬脂酰辅酶 A 去饱和酶-1（SCD-1）在 EDL 中的表达大约比 SOL 肌肉高 13 倍，但在两种肌肉中都没有因 HFD 而改变。Elongase-5 的表达在 EDL 中高于 SOL 肌肉，而 Elongase-6（Elovl6）的表达在两种饮食中都低于 SOL 肌肉。在 EDL 肌肉中，与 SLD 相比，HFD 中的 Elovl6 表达降低。FA 摄取、表达以及 FA 去饱和和延长酶的饮食诱导变化的模式保持了 EDL 肌肉中较高的 FA 不饱和度。因此，骨骼肌的纤维类型组成及其分布可能在肥胖和 IR 的发生和发展中起重要作用。
