Lushaj Entela Bua, Johnson Jody K, McKenzie Debbie, Aiken Judd M
Institute on Aging, School of Public Health, Department of Comparative Biosciences, University of Wisconsin, 1656 Linden Drive, Madison, WI 53706, USA.
J Gerontol A Biol Sci Med Sci. 2008 Sep;63(9):921-7. doi: 10.1093/gerona/63.9.921.
Although the age-dependent loss of muscle mass and strength, sarcopenia, is an inevitable process, its onset and progression are not well established. Here we defined the onset and the progression of sarcopenia in a healthy aging animal model, Fisher 344xBrown Norway rats. Vastus lateralis, rectus femoris, and vastus medialis muscles (three of the quadriceps muscles) were analyzed at 5 months of age and at 3-month intervals between 12 and 39 months of age. We found an age-dependent decline in muscle mass and fiber number and an increase in fiber atrophy and nonmuscle tissue. Significant changes of fiber number and muscle mass were not observed until very late in life (30-33 months) and were concurrent, whereas fiber cross-sectional area (CSA) gradually declined from maximum CSA (24 months). Sarcopenic declines identified between 30 and 36 months did not continue to 39 months, possibly due to the increased proportion of type I fibers.
尽管与年龄相关的肌肉质量和力量丧失，即肌肉减少症，是一个不可避免的过程，但其发病和进展尚未完全明确。在此，我们在健康衰老动物模型——费希尔344×布朗挪威大鼠中定义了肌肉减少症的发病和进展。在5月龄以及12至39月龄之间每隔3个月对股外侧肌、股直肌和股内侧肌（股四头肌中的三块肌肉）进行分析。我们发现肌肉质量和纤维数量随年龄下降，纤维萎缩和非肌肉组织增加。直到生命后期（30 - 33月龄）才观察到纤维数量和肌肉质量的显著变化，且二者同时出现，而纤维横截面积（CSA）从最大CSA（24月龄）开始逐渐下降。在30至36月龄之间确定的肌肉减少症衰退在39月龄时并未持续，这可能是由于I型纤维比例增加所致。
