Pistilli Emidio E, Siu Parco M, Alway Stephen E
Laboratory of Muscle biology and Sarcopenia, Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506-9227, USA.
J Gerontol A Biol Sci Med Sci. 2006 Mar;61(3):245-55. doi: 10.1093/gerona/61.3.245.
This study tested the hypothesis that aging exacerbates apoptotic signaling in rat fast plantaris muscle during muscle unloading. Plantaris muscle mass was 22% lower in aged animals and the apoptotic index was 600% higher, when compared to those in young adult animals. Following 14 days of hind-limb unloading, absolute plantaris muscle mass was 20% lower in young adult animals with a corresponding 200% higher elevation of the apoptotic index. Unloading had no affect on muscle weight or apoptotic index of aged plantaris muscles. The changes in pro-apoptotic messenger RNA (mRNA) for apoptotic protease activating factor-1 (Apaf-1), Bax, and inhibitor of differentiation protein-2 (Id2) were exacerbated with aging. Bax and Bcl-2 protein levels were also altered differently in aged muscle, compared to young. Significant positive correlations were observed between the changes in Id2 and Bax mRNA, and Id2 and caspase-9 mRNA. These data suggest that a pro-apoptotic environment may contribute to aging-associated atrophy in fast skeletal muscle, but apoptotic signaling differs by age.
衰老会加剧大鼠比目鱼肌在肌肉卸载过程中的凋亡信号。与年轻成年动物相比，老年动物的比目鱼肌质量降低了22%，凋亡指数高出600%。在进行14天的后肢卸载后，年轻成年动物的比目鱼肌绝对质量降低了20%，相应地凋亡指数升高了200%。卸载对老年比目鱼肌的肌肉重量或凋亡指数没有影响。随着衰老，凋亡蛋白酶激活因子-1（Apaf-1）、Bax和分化抑制蛋白-2（Id2）等促凋亡信使核糖核酸（mRNA）的变化加剧。与年轻肌肉相比，老年肌肉中Bax和Bcl-2蛋白水平的变化也有所不同。在Id2与Bax mRNA的变化之间，以及Id2与半胱天冬酶-9 mRNA的变化之间，观察到显著的正相关。这些数据表明，促凋亡环境可能导致快速骨骼肌中与衰老相关的萎缩，但凋亡信号因年龄而异。
