Bone adaptation in response to treadmill exercise in young and adult mice.
Bone adaptation in response to treadmill exercise in young and adult mice.
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DOI：
10.1016/j.bonr.2018.01.003
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发表时间：
2018-06-01
期刊：
影响因子：
2.5
通讯作者：
Zhang, Chunbin
中科院分区：
文献类型：
--
作者：
Gardinier, Joseph D;Rostami, Niloufar;Zhang, Chunbin
运动是决定骨折风险的关键因素，也是促进骨形成的一种临床手段。然而，运动增加骨量的效果随着年龄的增长而下降。这项研究的目的是在细胞和组织水平上确定与年龄相关的运动合成代谢反应的差异。为此，年轻的(8周大的)和成年的(36周大的)雄性小鼠接受在跑步机上跑步的适度运动方案。因此，运动在第一周对PTHrP和SOST基因的表达有显著影响，这与年龄有关。特别是，幼鼠表现出PTHrP表达的增加和SOST的表达的降低，这两种情况在成年小鼠中都没有受到运动的影响。运动5周后，幼龄小鼠骨细胞在蛋白质水平表达硬化素的百分比显著下降，而成年小鼠未见明显下降。对胫骨的力学测试发现，锻炼对组织水平的力学性能有显著影响，特别是与年龄有关的极限应力和弹性系数。特别是成年小鼠，尽管与久坐不动的对照组相比，皮质面积和皮质厚度增加，但其模数显著下降。总而言之，这项研究表明，随着年龄的增长，细胞对运动的反应发生了变化，成年阶段骨量的增加并不能改善骨骼强度。
Exercise is a key determinate of fracture risk and provides a clinical means to promote bone formation. However, the efficacy of exercise to increase bone mass declines with age. The purpose of this study was to identify age-related differences in the anabolic response to exercise at the cellular and tissue level. To this end, young (8-weeks of age) and adult (36-weeks of age) male mice were subjected to a moderate exercise regimen of running on a treadmill. As a result, exercise had a significant effect on PTHrP and SOST gene expression during the first week that was dependent upon age. In particular, young mice displayed an increase in PTHrP expression and decrease in SOST expression, both of which remained unaffected by exercise in the adult mice. After 5-weeks of exercise, a significant decrease in the percentage of osteocytes expressing sclerostin at the protein level was found in young mice, but not adult mice. Mechanical testing of the tibia found exercise to have a significant influence on tissue-level mechanical properties, specifically ultimate-stress and modulus that was dependent on age. Adult mice in particular experienced a significant decrease in modulus despite an increase in cortical area and cortical thickness compared to sedentary controls. Altogether, this study demonstrates a shift in the cellular response to exercise with age, and that gains in bone mass at the adult stage fail to improve bone strength.