Testosterone supplementation during energy deficit promotes whole-body lean mass accretion, but the mechanisms underlying that effect remain unclear. To elucidate those mechanisms, skeletal muscle molecular adaptations were assessed from muscle biopsies collected before (Resting), 1 h (Post) and 6 h (Recovery) after exercise and a mixed meal (40 g protein, 1 h post-exercise) following 14 days of weight maintenance (WM) and 28 days of an exercise- and diet-induced 55% energy deficit (ED) in 50 physically active, non-obese men treated with 200 mg testosterone enanthate/week (TEST) or placebo (PLA) during the ED. Participants (n=10/group) exhibiting substantial increases (TEST) in leg lean mass and total testosterone were compared to those exhibiting decreases in both of these measures (PLA). Resting androgen receptor (AR) protein content was higher and fibroblast growth factor-inducible 14 (Fn14), IL-6 receptor (IL-6R), and muscle ring-finger protein-1 (MuRF1) gene expression were lower in TEST versus PLA during ED relative to WM (P < 0.05). Changes in inflammatory, myogenic, and proteolytic gene expression did not differ between groups after exercise and recovery feeding. Mechanistic target of rapamycin (mTOR) signaling (i.e., translational efficiency) was also similar between groups at rest and after exercise and the mixed meal. Muscle total RNA content (i.e., translational capacity) increased more during ED in TEST than PLA (P < 0.05). These findings indicate that attenuated proteolysis at rest, possibly downstream of AR, Fn14, and IL-6R signaling, and increased translational capacity, not efficiency, may drive lean mass accretion with testosterone administration during energy deficit.

中文翻译：

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睾酮补充剂在严重能量缺乏期间上调雄激素受体表达和翻译能力。

在能量不足期间补充睾酮可促进全身瘦体重增加，但这种影响背后的机制仍不清楚。为了阐明这些机制，骨骼肌分子适应性从运动前（休息）、运动后 1 小时（运动后）和 6 小时（恢复）收集的肌肉活检以及 14 50 名身体活跃的非肥胖男性每周接受 200 毫克庚酸睾酮 (TEST) 或安慰剂 (PLA) 治疗，体重维持 (WM) 天数和运动和饮食导致 55% 能量不足 (ED) 天数 28 天在 ED 期间。将腿部瘦体重和总睾酮显着增加 (TEST) 的参与者 (n = 10/组) 与在这两种测量 (PLA) 中表现出下降的参与者进行比较。TEST 与 PLA 相比，静息雄激素受体 (AR) 蛋白含量较高，成纤维细胞生长因子诱导型 14 (Fn14)、IL-6 受体 (IL-6R) 和肌肉环指蛋白-1 (MuRF1) 基因表达较低在 ED 期间相对于 WM (P < 0.05)。运动和恢复喂养后，各组之间炎症、肌原性和蛋白水解基因表达的变化没有差异。雷帕霉素 (mTOR) 信号转导的机制靶点（即翻译效率）在休息组和运动后以及混合膳食组之间也相似。TEST ED 期间肌肉总RNA 含量（即翻译能力）比PLA 增加更多（P < 0.05）。这些发现表明静息时蛋白水解减弱，可能是 AR、Fn14 和 IL-6R 信号传导的下游，并增加了翻译能力，而不是效率，