Ryan Alice S, Li Guoyan
Department of Veterans Affairs, Department of Medicine, Division of Gerontology and Palliative Medicine, and the Baltimore VA Medical Center Geriatrics, Research, Education Center (GRECC), VA Maryland Health Care System, Baltimore, MD 21201, USA.
JCSM Clin Rep. 2021 Oct;6(4):137-142. doi: 10.1002/crt2.43. Epub 2021 Sep 23.
Myostatin (MSTN) is a key negative regulator of muscle mass in humans and animals, having direct and indirect influences on molecular regulators of atrophy and hypertrophy, thus potentially impacting fitness and physical function. We have shown that myostatin is elevated in conditions of chronic disability (e.g. paretic limb of stroke). Our hypothesis is that myostatin would be elevated in older adults with sarcopenia. The purpose of this study was to examine the role of skeletal muscle myostatin in sarcopenia.
Sixty-four overweight to obese aged 45-81 years underwent a maximal aerobic capacity (VOmax) test, dual-energy X-ray absorptiometry (DXA) scan to determine appendicular lean tissue (ALM), and muscle biopsy to determine myostatin mRNA expression by quantitative real time PCR (Q-RT-PCR). Rates of sarcopenia were determined using (ALM/BMI), and sarcopenia was defined as <0.789 in men and <0.512 in women. Subjects had low fitness (VOmax: 22.7 ± 0.7 mL/kg/min) and on average 40.9 ± 1% body fat.
The prevalence of sarcopenia in this cohort was 16%. BMI, % body fat, and fat mass were higher in adults with sarcopenia than those without sarcopenia (all < 0.001). Myostatin mRNA expression was lower in those without sarcopenia than those with sarcopenia ( < 0.05) and higher in men than women ( < 0.001). Myostatin expression was associated with BMI ( = 0.36, < 0.01) and mid-thigh intramuscular fat ( = 0.29, < 0.05).
Given that myostatin is important in muscle atrophy, fat accumulation, and sarcopenia, further work could address its implication in other aging cohorts of disability and chronic disease.
肌肉生长抑制素（MSTN）是人和动物肌肉量的关键负调节因子，对萎缩和肥大的分子调节因子有直接和间接影响，因此可能影响健康状况和身体功能。我们已经表明，在慢性残疾状态（如中风后的偏瘫肢体）下，肌肉生长抑制素水平会升高。我们的假设是，在患有肌肉减少症的老年人中，肌肉生长抑制素水平会升高。本研究的目的是探讨骨骼肌肌肉生长抑制素在肌肉减少症中的作用。
64名年龄在45 - 81岁的超重至肥胖者接受了最大有氧能力（VOmax）测试、双能X线吸收法（DXA）扫描以确定四肢瘦组织（ALM），并进行肌肉活检，通过定量实时PCR（Q - RT - PCR）确定肌肉生长抑制素mRNA表达。使用（ALM/BMI）确定肌肉减少症的发生率，男性肌肉减少症定义为<0.789，女性定义为<0.512。受试者健康状况不佳（VOmax：22.7±0.7 mL/kg/min），平均体脂率为40.9±1%。
该队列中肌肉减少症的患病率为16%。患有肌肉减少症的成年人的BMI、体脂百分比和脂肪量高于未患肌肉减少症的成年人（均P < 0.001）。未患肌肉减少症者的肌肉生长抑制素mRNA表达低于患肌肉减少症者（P < 0.05），男性高于女性（P < 0.001）。肌肉生长抑制素表达与BMI（r = 0.36，P < 0.01）和大腿中部肌内脂肪（r = 0.29，P < 0.05）相关。
鉴于肌肉生长抑制素在肌肉萎缩、脂肪堆积和肌肉减少症中很重要，进一步的研究可以探讨其在其他残疾和慢性疾病老年人群中的意义。
