运动与负荷对大鼠骨形态影响的无偏体视学观察

背景由于人体实验骨组织取材困难,骨组织形态体视学观察测定受到一定的限制.动物实验研究克服了人体实验此方面的局限性,可通过骨组织形态体视学观察测量直接评价骨质量.目的对大鼠进行运动与负荷实验,以探讨运动对青少年长骨发育影响的机制.设计以实验动物为研究对象,随机对照的实验研究.单位第四军医大学西京医院全军骨科重点实验.对象实验于2002-01/04北京体育大学运动实验室及第四军医大学西京医院全军骨科重点实验室完成.雄性4周龄SD大鼠120只,根据体质量随机搭配分成12组,每组10只.方法使大鼠进行不同强度的跑台运动,同时结合悬吊和负重模型,宰杀大鼠后做右侧胫骨不脱钙切片的四环素、钙黄绿素双荧光标记观察.采用体视学全视野无偏采样方法对不同强度运动和不同形式机械负荷的生长期大鼠骨量、骨结构、骨代谢等形态参数进行测试分析.主要观察指标①不同强度运动组间大鼠胫骨骨组织形态参数变化.②不同形式机械负荷组间骨小梁静态和动态参数的比较.结果低负荷运动组的骨的重量、骨量、骨结构和骨代谢等多项指标参数随增龄而增长或降低的变化较高负荷运动组和对照组规律.悬吊组骨矿沉积率显著减少,骨小梁相对体积显著减小、厚度明显增大、数量减少以及间距(或分离度)显著增大,其骨代谢生化标志物和生物力学性能低于低负荷运动组,而与对照组差异无显著性意义.负重组所有参数均与低负荷运动组相接近.其特点为骨形成和骨吸收活跃,但以骨形成为主;骨抵抗破坏的能力和抵抗变形的能力皆明显增强.结论不同强度的运动对生长期大鼠长骨发育可产生不同的影响,低负荷运动对骨代谢、骨量、骨组织形态以及骨生物力学等方面的综合作用好于高负荷运动.提示儿童少年在运动过程中,适当增加重力负荷,将有助于提高骨代谢和骨的力学性能,进而可提高发育过程中骨的质量.

Stereological observation without bias of the effects of exercises and loads on bone morphology in rats

BACKGROUND: Bone morphological stereological observation is limited due to the difficulty in human experimental bone access. Animal studies overcome the limitation of human experiments and can directly evaluate bone quality through bone stereological histomorphometric parameters.OBJECTIVE: To explore the mechanism of the impacts of exercise on long bone development in adolescents through exercise and load experiments in rats.DESIGN: A randomized controlled study by employing experimental animals as subjects.SETTING: Laboratory of Sports of Beijing University of Physical Education and the Key Laboratory of Orthopaedics of Xijing Hospital Affiliated to the Fourth Military Medical University of Chinese PLA.MATERIALS: The study was conducted in the Laboratory of Sports of Beijing University of Physical Education and the Key Laboratory of Orthopaedics of Xijing Hospital Affiliated to the Fourth Military Medical University of Chinese PLA. Totally 120 male 4-week old SD rats were randomly paired into 12 groups with 10 rats each based on their body mass.METHODS: Incremental exercises with the combination of suspension and loading mode of rats were used in the study. The undecalcified slices of the right tibia were observed after double-fluorescence-labeling by tetracycline (TC) and calcein for the analysis of bone histomorphometric parameters including bone mass, structure and metabolism, etc. During the period of growth under different exercise strength and different modes of mechanic load by stereological sampling without bias.static or dynamic parameters of bone trabecula among groups of different modes for mechanical load.RESULTS: The increase or decrease of multiple parameters including bone mass, bone quality, bone structure and bone metabolism in low-loading exercise group were more regular than that of high-loading exercise group and control group. In the suspension group, the bone mineral apposition significantly reduced, and the relative volume of bone trabecula significantly decreased with the significantly increased thickness, decreased numbers and significant of increased separation. The biochemical indicators of bone metabolism and the biomechanical capability of suspension group were significantly lower than that of low-loading exercise group but similar to that of control group. All parameters of loading group were similar to those of low-loading exercise group with the characters of active osteogenesis and osteo-absorption but mainly osteogenesis, and significantly enhanced abilities of anti-destruction and anti-deformity in bone.CONCLUSION: Exercises of different strengths can produce different impacts on long bone development in rats of growth period. The integrated effects of low-loading exercises in bone metabolism, bone mass, bone histomorphology and bone biomechanics are better than those of high-loading exercises. This phenomenon suggests that appropriate increment of gravity load during the exercise processin children and adolescents is good for the improvement of the capability of bone metabolism and bone mechanics, which further improve the bone quality during development.