Effect of flywheel-based resistance exercise on processes contributing to muscle atrophy during unloading in adult rats
Effect of flywheel-based resistance exercise on processes contributing to muscle atrophy during unloading in adult rats
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DOI：
10.1152/japplphysiol.01540.2005
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发表时间：
2006-07-01
影响因子：
3.3
通讯作者：
Peterson, Charlotte A.
中科院分区：
文献类型：
--
作者：
Dupont-Versteegden, Esther E.;Fluckey, James D.;Peterson, Charlotte A.
基于飞轮的阻力运动对成年大鼠卸载期间导致肌肉萎缩的过程的影响。 J Appl Physiol 101: 202-212, 2006。首次发表于 2006 年 4 月 6 日； doi：10.1152/japplpsyol。 01540.2005。基于飞轮的阻力运动 (RE) 可减轻后肢悬挂期间的肌肉萎缩。我们之前已经表明，RE 会导致蛋白质合成升高，但尚未研究其对蛋白质降解、细胞增殖或凋亡的影响。我们假设，除了影响蛋白质合成之外，RE 还能抑制后肢悬吊期间导致肌肉萎缩的过程。雄性大鼠被安置在普通笼子中（对照），尾部悬吊2周（HS），或每隔一天用RE进行HS 2周（HSRE）。尽管 RE 减轻了 HS 期间的比目鱼肌萎缩，但 HS 观察到的细胞凋亡增加了五倍，细胞增殖减少了 53%，而 RE 对此没有影响。编码泛素-蛋白酶体蛋白降解途径成分的基因表达随 HS 升高而升高，包括泛素、MAFbx、Murf-1、Nedd4 和 XIAP，以及蛋白酶体亚基 C2 和 C9。总泛素化蛋白随着 HS 的增加而增加，但蛋白酶体活性与对照没有不同。 RE 选择性地改变该途径不同成分的表达：MAFbx、Murf-1 和泛素 mRNA 丰度下调，而 C2 和 C9 亚基仍然升高。同样，Nedd4 和 XIAP 继续上调，这可能是观察到 RE 导致总泛素化蛋白增加的原因。因此，由于泛素连接酶组成的改变，不同的蛋白质群可能被 RE 泛素化。总之，本研究中使用的基于飞轮的阻力运动范式与抑制与肌肉萎缩相关的一些机制有关，例如 MAFbx 和 Murf-1 的增加，但与其他机制无关，例如蛋白酶体亚基重塑、细胞凋亡和增殖减少，这可能是无法完全恢复肌肉质量的原因。确定影响后面这些过程的具体运动参数可能有助于设计老年人或太空飞行期间的有效运动策略。
Effect of flywheel-based resistance exercise on processes contributing to muscle atrophy during unloading in adult rats. J Appl Physiol 101: 202-212, 2006. First published April 6, 2006; doi: 10.1152/japplphysiol. 01540.2005. Flywheel-based resistance exercise (RE) attenuates muscle atrophy during hindlimb suspension. We have previously shown that protein synthesis is elevated in response to RE, but the effect on protein degradation, cell proliferation, or apoptosis was not investigated. We hypothesized that, in addition to affecting protein synthesis, RE inhibits processes that actively contribute to muscle atrophy during hindlimb suspension. Male rats were housed in regular cages (control), tail suspended for 2 wk (HS), or HS with RE every other day for 2 wk (HSRE). Although RE attenuated soleus muscle atrophy during HS, the observed fivefold elevation in apoptosis and the 53% decrease in cell proliferation observed with HS were unaffected by RE. Expression of genes encoding components of the ubiquitin-proteasome pathway of protein degradation were elevated with HS, including ubiquitin, MAFbx, Murf-1, Nedd4, and XIAP, and proteasome subunits C2 and C9. Total ubiquitinated protein was increased with HS, but proteasome activity was not different from control. RE selectively altered the expression of different components of this pathway: MAFbx, Murf-1, and ubiquitin mRNA abundance were downregulated, whereas C2 and C9 subunits remained elevated. Similarly, Nedd4 and XIAP continued to be upregulated, potentially accounting for the observed augmentation in total ubiquitinated protein with RE. Thus a different constellation of proteins is likely ubiquitinated with RE due to altered ubiquitin ligase composition. In summary, the flywheel-based resistance exercise paradigm used in this study is associated with the inhibition of some mechanisms associated with muscle atrophy, such as the increase in MAFbx and Murf-1, but not with others, such as proteasome subunit remodeling, apoptosis, and decreased proliferation, potentially accounting for the inability to completely restore muscle mass. Identifying specific exercise parameters that affect these latter processes may be useful in designing effective exercise strategies in the elderly or during spaceflight.