Military Nutrit ion Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA.
Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA.
J Clin Endocrinol Metab. 2022 Jul 14;107(8):e3254-e3263. doi: 10.1210/clinem/dgac295.
Effects of testosterone on integrated muscle protein metabolism and muscle mass during energy deficit are undetermined.
The objective was to determine the effects of testosterone on mixed-muscle protein synthesis (MPS), proteome-wide fractional synthesis rates (FSR), and skeletal muscle mass during energy deficit.
This was a randomized, double-blind, placebo-controlled trial.
The study was conducted at Pennington Biomedical Research Center.
Fifty healthy men.
The study consisted of 14 days of weight maintenance, followed by a 28-day 55% energy deficit with 200 mg testosterone enanthate (TEST, n = 24) or placebo (PLA, n = 26) weekly, and up to 42 days of ad libitum recovery feeding.
Mixed-MPS and proteome-wide FSR before (Pre), during (Mid), and after (Post) the energy deficit were determined using heavy water (days 1-42) and muscle biopsies. Muscle mass was determined using the D3-creatine dilution method.
Mixed-MPS was lower than Pre at Mid and Post (P < 0.0005), with no difference between TEST and PLA. The proportion of individual proteins with numerically higher FSR in TEST than PLA was significant by 2-tailed binomial test at Post (52/67; P < 0.05), but not Mid (32/67; P > 0.05). Muscle mass was unchanged during energy deficit but was greater in TEST than PLA during recovery (P < 0.05).
The high proportion of individual proteins with greater FSR in TEST than PLA at Post suggests exogenous testosterone exerted a delayed but broad stimulatory effect on synthesis rates across the muscle proteome during energy deficit, resulting in muscle mass accretion during subsequent recovery.
睾酮对能量亏空时肌肉蛋白质代谢和肌肉质量的综合影响尚不确定。
本研究旨在确定睾酮对能量亏空时混合肌肉蛋白质合成（MPS）、蛋白质组范围的合成速率分数（FSR）和骨骼肌质量的影响。
这是一项随机、双盲、安慰剂对照试验。
本研究在彭宁顿生物医学研究中心进行。
50 名健康男性。
研究包括 14 天的体重维持，随后进行 28 天 55%的能量亏空，每周给予 200mg 庚酸睾酮（TEST，n=24）或安慰剂（PLA，n=26），并进行长达 42 天的随意恢复喂养。
使用重水（第 1-42 天）和肌肉活检在能量亏空前（Pre）、期间（Mid）和之后（Post）测定混合 MPS 和蛋白质组范围的 FSR。肌肉质量通过 D3-肌酸稀释法测定。
混合 MPS 在 Mid 和 Post 时均低于 Pre（P<0.0005），TEST 和 PLA 之间无差异。通过 2 尾二项式检验，在 Post（52/67；P<0.05）时，TEST 中比 PLA 中具有更高 FSR 的个体蛋白质比例显著高于 PLA，但在 Mid（32/67；P>0.05）时则没有。能量亏空期间肌肉质量不变，但恢复期间 TEST 组大于 PLA 组（P<0.05）。
在 Post 时，TEST 中比 PLA 中具有更高 FSR 的个体蛋白质比例较高，表明外源性睾酮在能量亏空期间对肌肉蛋白质组的合成速率产生了延迟但广泛的刺激作用，导致随后恢复期间肌肉质量增加。
