Fellner Claudia, Schick Fritz, Kob Robert, Hechtl Christine, Vorbuchner Marianne, Büttner Roland, Hamer Okka W, Sieber Cornel C, Stroszczynski Christian, Bollheimer L Cornelius
Institute of Radiology, University Hospital Regensburg, Regensburg, Germany.
Gerontology. 2014;60(6):530-8. doi: 10.1159/000360289. Epub 2014 Jun 11.
Knowledge about the molecular pathomechanisms of sarcopenia is still sparse, especially with regard to nutritional risk factors and the subtype of sarcopenic obesity.
The aim of this study was to characterize diet-induced and age-related changes on the quality and quantity of the quadriceps muscle in a rat model of sarcopenia by different magnetic resonance (MR) techniques.
A total of 36 6-month-old male Sprague-Dawley rats were randomly subdivided into 2 groups and received either a high-fat diet (HFD) or a control diet (CD). At the age of 16 months, 15 HFD and 18 CD rats underwent MR at 1.5 T. T1-weighted images as well as T2 relaxation time maps were acquired perpendicular to the long axis of the quadriceps muscles. Maximum cross-sectional area (CSA) of the quadriceps muscle was measured on T1-weighted images, and T2 relaxation times of muscle were assessed in a region without visible intramuscular fat (T2lean muscle) and across the complete CSA (T2muscle). Furthermore, (1)H-MR spectroscopy was performed to evaluate the relative lipid content of the quadriceps muscles. These measurements were repeated 5 months later in the surviving 8 HFD and 14 CD rats.
HFD rats revealed significantly decreased CSA and CSA per body weight (BW) as well as prolonged T2 relaxation times of muscle. A higher weight gain (upper tertile during the first 6 months of diet in CD rats) resulted in a significant change of T2muscle, but had no relevant impact on CSA. Advancing age up to 21 months led to significantly decreased BW, CSA and CSA/BW, significantly prolonged T2muscle and T2lean muscle and enlarged lipid content in the quadriceps muscle.
In an experimental setting a chronically fat-enriched diet was shown to have a relevant and age-associated influence on both muscle quantity and quality. By translational means the employed MR techniques give rise to the possibility of an early detection and noninvasive quantification of sarcopenia in humans, which is highly relevant for the field of geriatrics.
关于肌肉减少症分子发病机制的知识仍然匮乏，尤其是在营养风险因素和肌肉减少性肥胖亚型方面。
本研究的目的是通过不同的磁共振（MR）技术，在肌肉减少症大鼠模型中，表征饮食诱导和年龄相关的股四头肌质量和数量变化。
总共36只6个月大的雄性Sprague-Dawley大鼠被随机分为2组，分别给予高脂饮食（HFD）或对照饮食（CD）。在16个月大时，15只HFD大鼠和18只CD大鼠在1.5T下进行磁共振成像。获取垂直于股四头肌长轴的T1加权图像以及T2弛豫时间图。在T1加权图像上测量股四头肌的最大横截面积（CSA），并在无可见肌内脂肪的区域（T2瘦肌肉）和整个CSA范围内（T2肌肉）评估肌肉的T2弛豫时间。此外，进行（1）H-磁共振波谱分析以评估股四头肌的相对脂质含量。5个月后，对存活的8只HFD大鼠和14只CD大鼠重复这些测量。
HFD大鼠的CSA和每体重（BW）的CSA显著降低，肌肉的T2弛豫时间延长。更高的体重增加（CD大鼠在饮食的前六个月中处于上三分位数）导致T2肌肉有显著变化，但对CSA没有相关影响。年龄增长至21个月导致BW、CSA和CSA/BW显著降低，T2肌肉和T2瘦肌肉显著延长，股四头肌中的脂质含量增加。
在实验环境中，长期富含脂肪的饮食对肌肉数量和质量具有相关且与年龄相关的影响。通过转化手段，所采用的MR技术为早期检测和无创定量人类肌肉减少症提供了可能性，这在老年医学领域具有高度相关性。
