Université Clermont Auvergne, INRA, Unité de Nutrition Humaine, UMR1019, F-63000 CLERMONT-FERRAND, France.
Nutrients. 2019 Feb 8;11(2):355. doi: 10.3390/nu11020355.
Elevated plasma branched-chain amino acids (BCAA) levels are often observed in obese insulin-resistant (IR) subjects and laboratory animals. A reduced capacity of the adipose tissues (AT) to catabolize BCAA has been proposed as an explanation, but it seems restricted to obesity models of genetically modified or high fat⁻fed rodents. We aimed to determine if plasma BCAA levels were increased in a model of IR without obesity and to explore the underlying mechanisms. Rats were fed with a standard diet, containing either starch or fructose. BCAA levels, body weight and composition were recorded before and after 5, 12, 30, or 45 days of feeding. Elevated blood BCAA levels were observed in our IR model with unaltered body weight and composition. No changes were observed in the liver or the AT, but instead an impaired capacity of the skeletal muscle to catabolize BCAA was observed, including reduced capacity for transamination and oxidative deamination. Although the elevated blood BCAA levels in the fructose-fed rat seem to be a common feature of the IR phenotype observed in obese subjects and high fat⁻fed animals, the mechanisms involved in such a metabolic phenomenon are different, likely involving the skeletal muscle BCAA metabolism.
血浆支链氨基酸（BCAA）水平升高通常在肥胖胰岛素抵抗（IR）患者和实验动物中观察到。有人提出，脂肪组织（AT）分解 BCAA 的能力降低是一种解释，但这种情况似乎仅限于基因修饰或高脂肪喂养的啮齿动物的肥胖模型。我们旨在确定在没有肥胖的 IR 模型中是否会增加血浆 BCAA 水平，并探讨其潜在机制。大鼠分别用含有淀粉或果糖的标准饮食喂养。在喂养 5、12、30 或 45 天后，记录 BCAA 水平、体重和组成。在我们的 IR 模型中，观察到了体重和组成未改变的血液 BCAA 水平升高。肝脏或 AT 没有变化，但骨骼肌分解 BCAA 的能力受损，包括转氨基和氧化脱氨基能力降低。尽管果糖喂养大鼠的血液 BCAA 水平升高似乎是肥胖患者和高脂肪喂养动物中观察到的 IR 表型的共同特征，但涉及这种代谢现象的机制不同，可能涉及骨骼肌 BCAA 代谢。
