A single day of bed rest, irrespective of energy balance, does not affect skeletal muscle gene expression or insulin sensitivity
A single day of bed rest, irrespective of energy balance, does not affect skeletal muscle gene expression or insulin sensitivity
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DOI：
10.1113/ep086961
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发表时间：
2018-06-01
影响因子：
2.7
通讯作者：
Wall, Benjamin T.
中科院分区：
文献类型：
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作者：
Dirks, Marlou L.;Stephens, Francis B.;Wall, Benjamin T.
支持废用引起的骨骼肌功能失调的初始代谢和分子事件以及能量平衡的贡献仍有待研究。十名年轻健康男性（年龄 25 +/- 1 岁；体重指数 25.3 +/- 0.8kgm(-2)）以随机、交叉的方式进行了三个 24 小时实验室实验：（i）通过能量平衡饮食（CON）控制习惯性体力活动； (ii) 严格卧床休息并饮食以维持能量平衡（BR-B）； (iii) 严格卧床休息，饮食与 CON 相同，从而实现正能量平衡。每次就诊期间均进行连续血糖监测，并在前后进行股外侧肌活检和口服葡萄糖耐量测试。与之前7天卧床研究中收集的肌肉样本并行，活检被用来检查与肌肉质量和胰岛素敏感性调节相关的基因的表达。无论能量平衡如何，卧床休息一天都不会导致全身底物氧化、胰岛素敏感性指数[即胰岛素敏感性指数]发生明显变化。胰岛素抵抗的稳态模型评估，BR-B从2.7 +/- 1.7到3.1 +/- 1.5 (P>0.05)和松田指数，BR-B从5.9 +/- 3.3到5.2 +/- 2.9 (P>0.05)]或与CON相比的24小时血糖控制/变异性。卧床休息 7 天导致胰岛素信号传导、脂质储存/氧化和肌肉蛋白分解相关基因的表达降低约 30-55%，而卧床休息 1 天后没有观察到此类变化。总之，需要超过一天的身体不活动才能观察与卧床休息相关的胰岛素抵抗和强大的骨骼肌转录反应以及随后的能量平衡变化。
The initial metabolic and molecular events that underpin disuse-induced skeletal muscle deconditioning, and the contribution of energy balance, remain to be investigated. Ten young, healthy men (age 25 +/- 1years; body mass index 25.3 +/- 0.8kgm(-2)) underwent three 24h laboratory-based experimental periods in a randomized, crossover manner: (i) controlled habitual physical activity with an energy-balanced diet (CON); (ii) strict bed rest with a diet to maintain energy balance (BR-B); and (iii) strict bed rest with a diet identical to CON, consequently resulting in positive energy balance. Continuous glucose monitoring was performed throughout each visit, with vastus lateralis muscle biopsies and an oral glucose tolerance test performed before and after. In parallel with muscle samples collected from a previous 7day bed rest study, biopsies were used to examine the expression of genes associated with the regulation of muscle mass and insulin sensitivity. A single day of bed rest, irrespective of energy balance, did not lead to overt changes in whole-body substrate oxidation, indices of insulin sensitivity [i.e. homeostatic model assessment of insulin resistance, BR-B from 2.7 +/- 1.7 to 3.1 +/- 1.5 (P>0.05) and Matsuda index, BR-B from 5.9 +/- 3.3 to 5.2 +/- 2.9 (P>0.05)] or 24h glycaemic control/variability compared with CON. Seven days of bed rest led to approximate to 30-55% lower expression of genes involved in insulin signalling, lipid storage/oxidation and muscle protein breakdown, whereas no such changes were observed after 1day of bed rest. In conclusion, more than a single day of physical inactivity is required to observe the insulin resistance and robust skeletal muscle transcriptional responses associated with bed rest and consequent alterations in energy balance.