若齢期からの肥満歴が成熟期の骨格筋量に及ぼす影響

抄録

ABSTRACT 【Background and purpose】The effect of prolonged obesity history on muscle loss remains unknown; thus, it is necessary to investigate the influence of a prolonged obesity history on skeletal muscle before the onset of age-related muscle loss. The aim of the study was to investigate the influence of prolonged obesity history on skeletal muscle before the onset of age-related muscle loss. 【Methods】Young Sprague-Dawley rats were randomly divided into two groups: fed a normal diet (ND) or a high-fat diet (HFD). 【Results】The body weight was significantly higher in the HFD group than in the ND group at 11 weeks old. At 50 weeks old, the mean body weight of the HFD group was 1.3-fold higher than that of the ND group. There were no significant differences in the fasting glucose levels between the two groups. However, glucose levels after glucose administration were significantly higher in the HFD group than in the ND group after 32 and 49 weeks old, suggesting that prolonged obesity in young adults results in mild glucose intolerance in middle-aged rats. At 50 weeks old, histologically, many larger adipocytes were observed in the HFD group. However, indicators of chronic inflammation were not observed in the HFD group. Although absolute muscle loss was not observed in the HFD group, low relative muscle mass was detected with downregulation of interleukin 6, muscle RING finger protein 1, and atrogin-1 in the skeletal muscle. 【Discussion】Downregulation of these factors before the onset of age-related muscle loss could be an indicator of muscle loss in older adults with a history of prolonged obesity.