Pauk Martina, Amigo-Benavent Miryam, Patel Bijal, Jakeman Philip M, Carson Brian P
Food for Health Ireland, University of Limerick, Limerick, Ireland.
Department of Physical Education & Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland.
Am J Physiol Cell Physiol. 2025 Feb 1;328(2):C595-C603. doi: 10.1152/ajpcell.00117.2024. Epub 2025 Jan 13.
In this study, we used an ex vivo-in vitro model to assess the effect of feeding older (50-70 yr) adults a casein protein hydrolysate (CPH) compared with nonbioactive nonessential amino acid (NEAA) supplement on muscle protein synthesis (MPS) and markers of muscle protein breakdown (MPB). As a secondary objective, to assess any attenuation with aging, we compared the anabolic response to CPH-fed serum from older and young adults. Serum from seven healthy older and seven young men following overnight fast and 60-min postprandial ingestion of CPH or NEAA (0.33 g·kg body mass) was used to condition C2C12 myotube media. Analysis by two-way ANOVA of the fed relative to fasted MPS response revealed a main effect for protein type in pmTOR ( = 0.009), p70S6K ( = 0.031), p4E-BP1 ( = 0.047), and MPS ( = 0.041) with a greater response to CPH-fed serum, and interaction effects (age × protein) between young and old serum for pmTOR ( = 0.009) and p70S6K ( = 0.016). In addition, significant changes in myotube diameter ( = 0.049), atrogin-1 ( = 0.004), and MuRF-1 ( = 0.012) in response to CPH-fed compared with fasted serum were observed with no differences between young and old serum. In conclusion, this study demonstrated that CPH-fed serum from both young and older (50-70 yr) adults can stimulate MPS and muscle growth and can suppress biomarkers of muscle protein breakdown processes. This study extended previously developed coculture models and found that treating skeletal muscle cells with ex vivo human serum following feeding with a casein protein hydrolysate resulted in greater protein signaling, muscle protein synthesis, muscle growth, and lower expression of genes related to muscle protein breakdown compared with feeding with a nonessential amino acid control. These findings were similar using serum from young and older adults.
在本研究中，我们使用了一种体外-体内模型，以评估给年长（50-70岁）成年人喂食酪蛋白水解物（CPH）与非生物活性非必需氨基酸（NEAA）补充剂相比，对肌肉蛋白质合成（MPS）和肌肉蛋白质分解（MPB）标志物的影响。作为次要目标，为了评估衰老导致的任何衰减，我们比较了年长和年轻成年人对CPH喂养血清的合成代谢反应。来自7名健康年长男性和7名年轻男性的血清，在禁食过夜以及餐后60分钟摄入CPH或NEAA（0.33 g·kg体重）后，用于处理C2C12肌管培养基。通过双向方差分析对喂食后相对于禁食的MPS反应进行分析，结果显示在pmTOR（P = 0.009）、p70S6K（P = 0.031）、p4E-BP1（P = 0.047）和MPS（P = 0.041）中，蛋白质类型有主要效应，对CPH喂养血清的反应更大，并且年轻和年长血清之间在pmTOR（P = 0.009）和p70S6K（P = 0.016）方面存在交互作用（年龄×蛋白质）。此外，观察到与禁食血清相比，CPH喂养血清导致肌管直径（P = 0.049）、atrogin-1（P = 0.004）和MuRF-1（P = 0.012）有显著变化，年轻和年长血清之间无差异。总之，本研究表明，来自年轻和年长（50-70岁）成年人的CPH喂养血清均可刺激MPS和肌肉生长，并可抑制肌肉蛋白质分解过程的生物标志物。本研究扩展了先前开发的共培养模型，发现与非必需氨基酸对照喂养相比，用酪蛋白水解物喂养后用体外人血清处理骨骼肌细胞可导致更大的蛋白质信号传导、肌肉蛋白质合成、肌肉生长以及与肌肉蛋白质分解相关基因的较低表达。使用年轻和年长成年人血清的这些发现相似。
