Exercise-induced changes in the cortical bone of growing mice are bone- and gender-specific
Exercise-induced changes in the cortical bone of growing mice are bone- and gender-specific
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DOI：
10.1016/j.bone.2006.12.002
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发表时间：
2007-04-01
期刊：
影响因子：
4.1
通讯作者：
Kohn, David H.
中科院分区：
文献类型：
--
作者：
Wallace, Joseph M.;Rajachar, Rupak M.;Kohn, David H.
骨折风险和骨的机械能力是骨量和组织质量的函数，而骨量和组织质量又取决于骨的机械环境。雄性小鼠对非负重运动的反应比雌性小鼠更大，导致与对照动物相比骨骼更大，更强壮。本研究的目的是检验这一假设，即在生长过程中短期负重跑步（从8周龄开始21天; 30分钟/天; 12米/分钟; 5度倾斜，7天/周）同样会对雄性小鼠股骨和胫骨的横截面几何形状和机械能力产生更大的影响。根据跑步时腿部的方向和胫骨与撞击点的接近程度，假设胫骨的反应最大。通过四点弯曲试验测定相对于对照组的骨密度相关变化，同时还评估了体积骨密度和横截面几何形状。对跑步的反应是骨骼和性别特异性的，男性跑步者表现出最大的影响。在雄性胫骨中，骨膜周长、皮质内周长、皮质面积、内侧-外侧宽度和惯性弯曲力矩相对于对照小鼠增加，这表明虽然在8至11周龄的这些小鼠中发生生长，但运动加速了这种生长，导致骨组织在研究的3周内更大的增加。运动增加了男性胫骨的组织水平应变失效和结构屈服后变形，但这些屈服后的好处是以降低屈服变形、结构和组织水平屈服强度以及组织水平极限强度为代价的。这些结果表明，运动叠加在增长加速增长相关的胫骨横截面尺寸的增加。运动也会影响这种形成骨的质量，显著影响结构和组织水平的机械性能。(c)2006年爱思唯尔公司All rights reserved.
Fracture risk and mechanical competence of bone are functions of bone mass and tissue quality, which in turn are dependent on the bone's mechanical environment. Male mice have a greater response to non-weight-bearing exercise than females, resulting in larger, stronger bones compared with control animals. The aim of this study was to test the hypothesis that short-term weight-bearing running during growth (21 days starting at 8 weeks of age; 30 min/day; 12 m/min; 5 degrees incline-, 7 days/week) would similarly have a greater impact on cross-sectional geometry and mechanical competence in the femora and tibiae of male mice versus females. Based on the orientation of the legs during running and the proximity of the tibia to the point of impact, this response was hypothesized to be greatest in the tibia. Exercise-related changes relative to controls were assayed by four-point bending tests, while volumetric bone mineral density and cross-sectional geometry were also assessed. The response to running was bone- and gender-specific, with male tibiae demonstrating the greatest effects. In male tibiae, periosteal perimeter, endocortical perimeter, cortical area, medial-lateral width and bending moment of inertia increased versus control mice suggesting that while growth is occurring in these mice between 8 and I I weeks of age, exercise accelerated this growth resulting in a greater increase in bone tissue over the 3 weeks of the study. Exercise increased tissue-level strain-to-failure and structural post-yield deformation in the male tibiae, but these post-yield benefits came at the expense of decreased yield deformation, structural and tissue-level yield strength and tissue-level ultimate strength. These results suggest that exercise superimposed upon growth accelerated growth-related increases in tibial cross-sectional dimensions. Exercise also influenced the quality of this forming bone, significantly impacting structural and tissue-level mechanical properties. (c) 2006 Elsevier Inc. All rights reserved.