UMR PNCA, AgroParisTech, INRA, Université Paris-Saclay, 75005 Paris, France.
UMR C2VN, Aix-Marseille Université, INSERM, INRAE, 13385 Marseille, France.
Nutrients. 2021 May 7;13(5):1567. doi: 10.3390/nu13051567.
Dietary intakes must cover protein and essential amino acid (EAA) requirements. For this purpose, different methods have been developed such as the nitrogen balance method, factorial method, or AA tracer studies. However, these methods are either invasive or imprecise, and the Food and Agriculture Organization of the United Nations (FAO, 2013) recommends new methods and, in particular, metabolomics. The aim of this study is to determine total protein/EAA requirement in the plasma and urine of growing rats.
36 weanling rats were fed with diets containing 3, 5, 8, 12, 15, and 20% protein for 3 weeks. During experimentation, urine was collected using metabolic cages, and blood from the portal vein and vena was taken at the end of the experiment. Metabolomics analyses were performed using LC-MS, and the data were analyzed with a multivariate analysis model, partial least Squares (PLS) regression, and independent component-discriminant analysis (ICDA). Each discriminant metabolite identified by PLS or ICDA was tested by one-way ANOVA to evaluate the effect of diet.
PLS and ICDA allowed us to identify discriminating metabolites between different diet groups. Protein deficiency led to an increase in the AA catabolism enzyme systems inducing the production of breakdown metabolites in the plasma and urine.
These results indicate that metabolites are specific for the state of EAA deficiency and sufficiency. Some types of biomarkers such as AA degradation metabolites appear to be specific candidates for protein/EAA requirement.
饮食摄入必须满足蛋白质和必需氨基酸（EAA）的需求。为此，已经开发了不同的方法，如氮平衡法、因子法或 AA 示踪研究。然而，这些方法要么具有侵入性，要么不够精确，联合国粮食及农业组织（FAO，2013 年）建议采用新的方法，特别是代谢组学方法。本研究的目的是确定生长大鼠血浆和尿液中的总蛋白质/EAA 需要量。
36 只断奶大鼠分别用含有 3%、5%、8%、12%、15%和 20%蛋白质的饮食喂养 3 周。在实验过程中，使用代谢笼收集尿液，并在实验结束时从门静脉和腔静脉采血。使用 LC-MS 进行代谢组学分析，使用多元分析模型、偏最小二乘（PLS）回归和独立成分判别分析（ICDA）对数据进行分析。通过单向方差分析（ANOVA）测试 PLS 或 ICDA 识别的每个判别代谢物，以评估饮食的影响。
PLS 和 ICDA 允许我们识别不同饮食组之间的判别代谢物。蛋白质缺乏会导致 AA 分解代谢酶系统增加，从而在血浆和尿液中产生分解代谢物。
这些结果表明，代谢物是 EAA 缺乏和充足状态的特异性标志物。一些类型的生物标志物，如 AA 降解代谢物，似乎是蛋白质/EAA 需要量的特异性候选标志物。
