Male mice housed in groups engage in frequent fighting and show a lower response to additional bone loading than females or individually housed males that do not fight.
Male mice housed in groups engage in frequent fighting and show a lower response to additional bone loading than females or individually housed males that do not fight.
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DOI：
10.1016/j.bone.2013.01.029
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发表时间：
2013-05
期刊：
影响因子：
4.1
通讯作者：
Price, Joanna S.
中科院分区：
文献类型：
--
作者：
Meakin, Lee B.;Sugiyama, Toshihiro;Galea, Gabriel L.;Browne, William J.;Lanyon, Lance E.;Price, Joanna S.
研究骨骼对机械载荷的生理适应性的实验通常采用在体内对骨骼施加动态载荷的模型，并评估由此产生的质量和结构的变化。这是不言自明的，骨骼只会表现出适应性的反应，如果应用的人工负荷环境在很大程度上不同于骨骼已经习惯了正常的功能负荷。一般认为，实验组之间的正常载荷是相似的。在这里报道的研究中，我们发现情况并非总是如此。选取雄性和雌性17周龄C57BL/6小鼠，每6只为一组，在右侧胫骨上隔日施加单次（40个周期）无创轴向载荷，在样品小鼠胫骨近端内侧表面产生2200 με，持续2周。这导致了女性骨量的适应性增加，而不是男性。观察发现，雄性和雌性在行为上的主要区别是，雄性每小时打架1.3次，而雌性从不打架。因此，我们将所有老鼠单独饲养。在雌性小鼠中，无论是分组小鼠还是个体小鼠，对皮质骨和小梁骨的负荷都有类似的显著成骨反应。相比之下，在雄性中，负重对照骨与未负重对照骨相比的适应性增加仅在单独饲养的动物中表现出来。我们对这些发现的解释是，群居的年轻成年雄性之间频繁的激烈战斗可能足以产生峰值应变和应变率，这些峰值应变和应变率等于或超过人工负荷产生的刺激。这表明了确保群体间身体活动一致的重要性。降低自然产生的应变环境的背景水平，可以在较低的载荷下证明对人工载荷的自适应响应。►各组小鼠的活动水平差异显著；男性倾向于打架，而女性则不会。►在群体雄性中，生理压力下对人工负荷的适应性反应较低，表明对战斗的预适应。在比较各组动物对负荷的适应性反应时，重要的是要确保活动水平相似。
Experiments to investigate bone's physiological adaptation to mechanical loading frequently employ models that apply dynamic loads to bones in vivo and assess the changes in mass and architecture that result. It is axiomatic that bones will only show an adaptive response if the applied artificial loading environment differs in a significant way from that to which the bones have been habituated by normal functional loading. It is generally assumed that this normal loading is similar between experimental groups. In the study reported here we found that this was not always the case. Male and female 17-week-old C57BL/6 mice were housed in groups of six, and a single episode (40 cycles) of non-invasive axial loading, engendering 2,200με on the medial surface of the proximal tibiae in sample mice, was applied to right tibiae on alternate days for two weeks. This engendered an adaptive increase in bone mass in females, but not males. Observation revealed the main difference in behaviour between males and females was that males were involved in fights 1.3 times per hour, whereas the females never fought. We therefore housed all mice individually. In females, there was a similar significant osteogenic response to loading in cortical and trabecular bone of both grouped and individual mice. In contrast, in males, adaptive increases in the loaded compared with non-loaded control bones was only apparent in animals housed individually. Our interpretation of these findings is that the frequent vigorous fighting that occurs between young adult males housed in groups could be sufficient to engender peak strains and strain rates that equal or exceed the stimulus derived from artificial loading. This indicates the importance of ensuring that physical activity is consistent between groups. Reducing the background level of the naturally engendered strain environment allows adaptive responses to artificial loading to be demonstrated at lower loads. ► Activity levels in mice housed in groups differ significantly; males tend to fight, females do not. ► In grouped males, the adaptive response to artificial loading at physiological strains is low suggesting pre-adaptation to fighting. ► When comparing adaptive responses to loading between groups of animals it is important to ensure activity levels are similar.
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影响因子：
64.8
作者：
Skarnes WC;Rosen B;West AP;Koutsourakis M;Bushell W;Iyer V;Mujica AO;Thomas M;Harrow J;Cox T;Jackson D;Severin J;Biggs P;Fu J;Nefedov M;de Jong PJ;Stewart AF;Bradley A
通讯作者：
Bradley A
影响因子：
3.5
作者：
Oyegbile, TO;Marler, CA
通讯作者：
Marler, CA
影响因子：
3.3
作者：
Lynch, Maureen E.;Main, Russell P.;van der Meulen, Marjolein C. H.
通讯作者：
van der Meulen, Marjolein C. H.
影响因子：
4.1
作者：
Mosley, JR;Lanyon, LE
通讯作者：
Lanyon, LE
影响因子：
4.1
作者：
Sugiyama, Toshihiro;Meakin, Lee B.;Price, Joanna S.
通讯作者：
Price, Joanna S.