Skeletal Muscle Disuse Atrophy Is Not Attenuated by Dietary Protein Supplementation in Healthy Older Men
Skeletal Muscle Disuse Atrophy Is Not Attenuated by Dietary Protein Supplementation in Healthy Older Men
复制标题
DOI：
10.3945/jn.114.194217
复制
发表时间：
2014-08-01
影响因子：
4.2
通讯作者：
van Loon, Luc J. C.
中科院分区：
文献类型：
--
作者：
Dirks, Marlou L.;Wall, Benjamin T.;van Loon, Luc J. C.
由于受伤或疾病，肌肉连续短时间停用，可能会导致肌肉质量随着年龄的增长而显著减少(肌萎缩症)。有人建议，增加饮食中的蛋白质含量可能是减轻肌肉废用性萎缩的有效饮食策略。我们假设，每天补充两次蛋白质可以在短暂的肢体制动期间保持肌肉质量。23名健康的老年男性(69+/-1岁)接受了5d的单腿膝关节固定，方法是使用全腿石膏(PRO组，n=11)或不添加蛋白质补充剂(蛋白质20.7g，碳水化合物9.3g，脂肪3.0g)每日2次。分别于制动前和制动后2d行股四头肌单层CT扫描和单腿1次重复最大力量试验，分别测定肌肉横截面积和小腿肌力。此外，还收集了肌肉活组织以评估肌肉纤维特征以及选定基因的mRNA和蛋白质表达。制动后股四头肌CSA分别下降1.5+/-0.7%(P<；0.05)和2.0+/-0.6%(P<；0.05)，肌力下降8.3+/-3.3%(P<；0.05)和9.3+/-1.6%(P<；0.05)，组间差异无统计学意义。骨骼肌肌抑制素、肌生成素和肌肉环指蛋白-1(MuRF1)的mRNA表达在制动后均增加(P<；0.05)，而肌肉萎缩F-box/atgen-1(MAFBx)的mRNA表达仅在PRO组增加(P<；0.05)。总而言之，补充膳食蛋白质(类似于每天两次20克)并不能减少健康老年男性在短期肌肉停用期间的肌肉损失。这项试验在Clinicaltrials.gov上注册为NCT01588808。
Short successive periods of muscle disuse, due to injury or illness, can contribute significantly to the loss of muscle mass with aging (sarcopenia). It has been suggested that increasing the protein content of the diet may be an effective dietary strategy to attenuate muscle disuse atrophy. We hypothesized that protein supplementation twice daily would preserve muscle mass during a short period of limb immobilization. Twenty-three healthy older (69 +/- 1 y) men were subjected to 5 d of one-legged knee immobilization by means of a full-leg cast with (PRO group; n = 11) or without (CON group; n = 12) administration of a dietary protein supplement (20.7 g of protein, 9.3 g of carbohydrate, and 3.0 g of fat) twice daily. Two d prior to and immediately after the immobilization period, single-slice computed tomography scans of the quadriceps and single-leg 1 repetition maximum strength tests were performed to assess muscle cross-sectional area (CSA) and leg muscle strength, respectively. Additionally, muscle biopsies were collected to assess muscle fiber characteristics as well as mRNA and protein expression of selected genes. Immobilization decreased quadriceps' CSAs by 1.5 +/- 0.7% (P < 0.05) and 2.0 +/- 0.6% (P < 0.05), and muscle strength by 8.3 +/- 3.3% (P < 0.05) and 9.3 +/- 1.6% (P < 0.05) in the CON and PRO groups, respectively, without differences between groups. Skeletal muscle myostatin, myogenin, and muscle RING-finger protein-1 (MuRF1) mRNA expression increased following immobilization in both groups (P < 0.05), whereas muscle atrophy F-box/atrogen-1 (MAFBx) mRNA expression increased in the PRO group only (P < 0.05). In conclusion, dietary protein supplementation (similar to 20 g twice daily) does not attenuate muscle loss during short-term muscle disuse in healthy older men. This trial was registered at clinicaltrials.gov as NCT01588808.