Differential Adaptive Response of Growing Bones From Two Female Inbred Mouse Strains to Voluntary Cage-Wheel Running.
Differential Adaptive Response of Growing Bones From Two Female Inbred Mouse Strains to Voluntary Cage-Wheel Running.
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作者：
Schlecht SH;Ramcharan MA;Yang Y;Smith LM;Bigelow EM;Nolan BT;Moss DE;Devlin MJ;Jepsen KJ
不同形态、成分和力学特征的骨骼对生长过程中负荷增加的表型反应还不是很清楚。我们测试了两个近交系小鼠的骨骼是否会对自愿的笼轮跑步表现出不同的反应，这两个品系的近交系小鼠集合了不同的特征集，以在成年时实现机械动态平衡。雌性A/J和C57BL6/J(B6)4周龄小鼠无限制地接触标准笼轮4周。A/J小鼠股骨较窄，矿化程度较高，B6小鼠股骨较宽，矿化程度较低。两个品系平均每天跑步2到9.5km，两个品系之间的平均距离没有显著差异(p 0.133)。运动后A/J股骨表现出合成代谢反应，与对照组相比，骨干总面积增加2.8%(Tt.Ar，p = 0.06)，皮质面积增加4.7%(Ct.Ar，p = 0.012)。相比之下，与对照组相比，运动的B6股骨显示出6.2%(p <； 0.001)的Tt.Ar(p <； 0.001)和6.7%的Ct.Ar(p = 0.133)，股骨显示出显著的骨髓填充(p = 0.002)。这些对运动的不同形态反应不依赖于每天的长跑，与对照组相比，运动A/J股骨的最大负荷(ML)增加了7.9%(p = 0.001)，而B6股骨的最大负荷(ML)没有变化。在肱骨观察到一致的反应，但没有观察到椎体。在单独负荷或强迫跑步机跑步的情况下，这种不同的锻炼结果以前没有观察到过。我们的发现表明，在生长过程中对运动的代谢反应中涉及到一些关键因素，需要进一步考虑以了解在生长过程中基因、运动、骨形态和全骨量是如何相互作用的。©2018作者。JBMR Plus由威利期刊公司代表美国骨与矿物研究学会出版。
The phenotypic response of bones differing in morphological, compositional, and mechanical traits to an increase in loading during growth is not well understood. We tested whether bones of two inbred mouse strains that assemble differing sets of traits to achieve mechanical homeostasis at adulthood would show divergent responses to voluntary cage‐wheel running. Female A/J and C57BL6/J (B6) 4‐week‐old mice were provided unrestricted access to a standard cage‐wheel for 4 weeks. A/J mice have narrow and highly mineralized femora and B6 mice have wide and less mineralized femora. Both strains averaged 2 to 9.5 km of running per day, with the average‐distance run between strains not significantly different (p = 0.133). Exercised A/J femora showed an anabolic response to exercise with the diaphyses showing a 2.8% greater total area (Tt.Ar, p = 0.06) and 4.7% greater cortical area (Ct.Ar, p = 0.012) compared to controls. In contrast, exercised B6 femora showed a 6.2% (p < 0.001) decrease in Tt.Ar (p < 0.001) and a 6.7% decrease in Ct.Ar (p = 0.133) compared to controls, with the femora showing significant marrow infilling (p = 0.002). These divergent morphological responses to exercise, which did not depend on the daily distance run, translated to a 7.9% (p = 0.001) higher maximum load (ML) for exercised A/J femora but no change in ML for exercised B6 femora compared to controls. A consistent response was observed for the humeri but not the vertebral bodies. This differential outcome to exercise has not been previously observed in isolated loading or forced treadmill running regimes. Our findings suggest there are critical factors involved in the metabolic response to exercise during growth that require further consideration to understand how genotype, exercise, bone morphology, and whole‐bone strength interact during growth. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.