1Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan. 525-8577.
FASEB J. 2014 Apr;28(4):1891-7. doi: 10.1096/fj.13-245480. Epub 2014 Jan 17.
Skeletal muscle can synthesize testosterone and 5α-dihydrotestosterone (DHT) from dehydroepiandrosterone (DHEA) via steroidogenic enzymes in vitro, but hormone levels and steroidogenic enzyme expression decline with aging. Resistance exercise has been shown to increase in plasma sex steroid hormone levels. However, it remains unclear whether resistance training can restore impaired steroidogenic enzyme expressions in older individuals. Six young and 13 older men were recruited, and muscle biopsies were taken from the vastus lateralis at basal state. The same group of older subjects underwent resistance training involving knee extension and flexion exercises for 12 wk, and post-training biopsies were performed 4-5 d after the last exercise session. Muscular sex steroid hormone levels and sex steroidgenesis-related enzyme expressions were significantly lower in older subjects than younger ones at baseline, but 12 wk of resistance training significantly restored hormone levels (DHEA: 432±26 at baseline, 682±31 pg/μg protein, DHT: 6.2±0.9 at baseline, 9.8±1.4 pg/μg protein). Furthermore, the steroidogenesis-related enzymes such as 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, and 5α-reductase expressions were significantly restored by resistance training. We conclude progressive resistance training restores age-related declines in sex steroidogenic enzyme and muscle sex steroid hormone levels in older men.
骨骼肌可以通过体外的甾体生成酶从脱氢表雄酮（DHEA）合成睾酮和 5α-二氢睾酮（DHT），但激素水平和甾体生成酶表达随年龄增长而下降。抗阻运动已被证明可以增加血浆性激素水平。然而，目前尚不清楚抗阻训练是否可以恢复老年人受损的甾体生成酶表达。招募了 6 名年轻男性和 13 名老年男性，在基线状态下从股外侧肌采集肌肉活检。同一组老年受试者进行了涉及伸膝和屈膝运动的 12 周抗阻训练，最后一次运动后 4-5 天进行了训练后活检。基线时，老年受试者的肌肉性激素水平和与性激素生成相关的酶表达明显低于年轻受试者，但 12 周的抗阻训练显著恢复了激素水平（DHEA：基线时 432±26 pg/μg 蛋白，682±31 pg/μg 蛋白；DHT：基线时 6.2±0.9 pg/μg 蛋白，9.8±1.4 pg/μg 蛋白）。此外，抗阻训练还显著恢复了与甾体生成相关的酶如 3β-羟甾脱氢酶（HSD）、17β-HSD 和 5α-还原酶的表达。我们的结论是，渐进式抗阻训练可以恢复老年男性与年龄相关的甾体生成酶和肌肉性激素水平下降。
