Russ D W, Acksel C, McCorkle K W, Edens N K, Garvey S M
David W. Russ, PT, Ph.D. Associate Professor, Division of Physical Therapy , School of Rehab and Communication Sciences, Ohio University, W279 Grover Center, Athens, OH 45701, (ph.)740-566-0022, (fax)740-593-0293,
J Nutr Health Aging. 2017;21(5):554-561. doi: 10.1007/s12603-016-0810-2.
Loss of skeletal muscle function is linked to increased risk for loss of health and independence in older adults. Dietary interventions that can enhance aging muscle function, alone or in combination with exercise, may offer an effective way to reduce these risks. The goal of this study was to evaluate the muscular effects of beta-hydroxy-beta-methylbutyrate (HMB) and beta-alanine (β-Ala) co-supplementation in aged Sprague-Dawley rats with voluntary access to running wheels (RW).
Aged (20 months) rats were housed with ad libitum access to RW while on a purified diet for 4 weeks, then balanced for RW activity and assigned to either a control or an experimental diet (control + HMB and β-Ala) for the next 4 weeks (n = 10/group). At the end of the study, we assessed muscle size, in situ force and fatigability in the medial gastrocnemius muscles, as well as an array of protein markers related to various age- and activity-responsive signaling pathways.
Dietary HMB+β-Ala did not improve muscle force or fatigue resistance, but a trend for increased muscle cross-sectional area (CSA) was observed (P = 0.077). As a result, rats on the experimental diet exhibited reduced muscle quality (force/CSA; P = 0.032). Dietary HMB+β-Ala reduced both the abundance of PGC1-α (P = 0.050) and the ratio of the lipidated to non-lipidated forms of microtubule-associated protein 1 light chain 3 beta (P = 0.004), markers of mitochondrial biogenesis and autophagy, respectively. Some alterations in myostatin signaling also occurred in the dietary HMB+β-Ala group. There was an unexpected difference (P = 0.046) in RW activity, which increased throughout the study in the animals on the control diet, but not in animals on the experimental diet.
These data suggest that the short-term addition of dietary HMB+β-Ala to modest physical activity provided little enhancement of muscle function in this model of uncomplicated aging.
骨骼肌功能丧失与老年人健康和独立性丧失风险增加有关。单独或与运动相结合的、可增强衰老肌肉功能的饮食干预措施，可能是降低这些风险的有效方法。本研究的目的是评估β-羟基-β-甲基丁酸酯（HMB）和β-丙氨酸（β-Ala）联合补充对可自由使用跑步轮（RW）的老年斯普拉格-道利大鼠肌肉的影响。
20月龄大鼠在纯化饮食条件下可自由使用RW饲养4周，然后根据RW活动情况进行平衡，并在接下来的4周内分为对照组或实验饮食组（对照组+HMB和β-Ala）（每组n = 10）。在研究结束时，我们评估了腓肠肌内侧的肌肉大小、原位力量和疲劳性，以及一系列与各种年龄和活动反应信号通路相关的蛋白质标志物。
饮食中补充HMB+β-Ala并未改善肌肉力量或抗疲劳能力，但观察到肌肉横截面积（CSA）有增加趋势（P = 0.077）。因此，食用实验饮食的大鼠肌肉质量降低（力量/CSA；P = 0.032）。饮食中补充HMB+β-Ala降低了过氧化物酶体增殖物激活受体γ共激活因子1α（PGC1-α）的丰度（P = 0.050）以及微管相关蛋白1轻链3β脂化形式与非脂化形式的比率（P = 0.004），这两个指标分别是线粒体生物发生和自噬的标志物。饮食中补充HMB+β-Ala组的肌肉生长抑制素信号也发生了一些变化。RW活动出现了意外差异（P = 0.046），在整个研究过程中，对照组动物的RW活动增加，而实验饮食组动物则没有。
这些数据表明，在这个简单衰老模型中，在适度体育活动基础上短期添加饮食HMB+β-Ala对肌肉功能的增强作用很小。
