Wein Silvia, Wolffram Siegfried, Schrezenmeir Jürgen, Gasperiková Daniela, Klimes Iwar, Seböková Elena
Diabetes and Nutrition Research Laboratory, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Diabetes Metab Res Rev. 2009 Feb;25(2):185-94. doi: 10.1002/dmrr.925.
High dietary intake of saturated fat impairs insulin sensitivity and lipid metabolism. The influence of fatty acid chain length, however, is not yet fully understood, but evidence exists for different effects of saturated long-chain (LC) versus saturated medium-chain (MC) fatty acids (FA).
To investigate the effects of the FA chain length, male Wistar rats were fed high-fat diets containing triacylglycerols composed of either MC- or LCFA for 4 weeks; rats fed maintenance diet served as a control. The animals underwent euglycemic hyperinsulinemic clamping or oral metabolic tolerance testing respectively; enzyme activities of mitochondrial (EC2.3.1.21 carnitine palmitoyl transferase) and peroxisomal (EC1.3.3.6 acyl-CoA oxidase) FA oxidation were measured in liver and muscle.
LCFA consumption resulted in higher fasted serum insulin and glucose concentrations compared to controls, while MCFA-fed animals did not differ from controls. Insulin sensitivity was reduced by 30% in the LCFA group while the MCFA group did not differ from controls. Feeding MCFA resulted in the controls' lowered fasted and post-prandial triacylglycerol concentration compared to LCFA, while triacylglycerol concentrations in muscle were higher in both high-fat groups compared to controls. No diet-induced changes were found in acyl-CoA oxidase (ACO) activity (liver and muscle), while LCFA feeding significantly raised carnitine palmitoyltransferase activity.
The chain length of saturated fatty acids in isocaloric diets affects insulin sensitivity, lipid metabolism and mitochondrial fatty acid oxidation without influencing body weight. While dietary LCFA clearly impair insulin sensitivity and lipid metabolism, MCFA seem to protect from lipotoxicity and subsequent insulin resistance without caloric restriction.
饮食中饱和脂肪摄入量高会损害胰岛素敏感性和脂质代谢。然而，脂肪酸链长度的影响尚未完全明确，但有证据表明饱和长链（LC）脂肪酸与饱和中链（MC）脂肪酸具有不同的作用。
为研究脂肪酸链长度的影响，给雄性Wistar大鼠喂食含由MC或LC脂肪酸组成的三酰甘油的高脂饮食4周；喂食维持饮食的大鼠作为对照。动物分别接受正常血糖高胰岛素钳夹试验或口服代谢耐量试验；测量肝脏和肌肉中线粒体（EC2.3.1.21肉碱棕榈酰转移酶）和过氧化物酶体（EC1.3.3.6酰基辅酶A氧化酶）脂肪酸氧化的酶活性。
与对照组相比，摄入LCFA导致空腹血清胰岛素和葡萄糖浓度更高，而喂食MCFA的动物与对照组无差异。LCFA组的胰岛素敏感性降低了30%，而MCFA组与对照组无差异。与LCFA相比，喂食MCFA导致对照组空腹和餐后三酰甘油浓度降低，而两个高脂组肌肉中的三酰甘油浓度均高于对照组。未发现饮食诱导的酰基辅酶A氧化酶（ACO）活性（肝脏和肌肉）变化，而喂食LCFA显著提高了肉碱棕榈酰转移酶活性。
等热量饮食中饱和脂肪酸的链长度影响胰岛素敏感性、脂质代谢和线粒体脂肪酸氧化，而不影响体重。虽然饮食中的LCFA明显损害胰岛素敏感性和脂质代谢，但MCFA似乎在不限制热量的情况下可防止脂毒性及随后的胰岛素抵抗。
