运动与限食对肥胖大鼠股骨骨密度和骨生物力学特性的影响

目的:研究运动与限食干预对肥胖大鼠股骨骨密度和骨生物力学特性的影响。方法:采用高脂饲料喂养建立肥胖大鼠模型,成功后将32只肥胖大鼠按体重随机分为限食组(7只)、运动组(9只)、运动并限食组(9只)、对照组(7只)。各组继续喂食高脂饲料,限食组喂食量为对照组的80%。运动组游泳5周,6d/周,90min/d。实验期间测量大鼠体重及Lee’s指数。最后一次运动结束后60小时宰杀大鼠,测量股骨长度、骨密度及骨生物力学特性参数。结果:(1)对体重的影响:运动、限食主效应显著(P<0.001或0.01),运动与限食交互作用不显著(P>0.05)。(2)对股骨长度和股骨骨密度的影响:运动、限食主效应不显著(P>0.05),运动与限食交互作用不显著(P>0.05)。(3)对股骨生物力学特性的影响:限食对肥胖大鼠股骨生物力学参数最大载荷、弹性载荷和最大能量主效应显著(P<0.01),运动与限食对其最大挠度、弹性挠度和刚性系数交互作用显著(P<0.01)。结论:(1)本研究的运动或限食干预能显著降低肥胖大鼠体重,但对其股骨长度、骨密度未产生显著影响。(2)限食干预使肥胖大鼠股骨硬度下降,抗断裂能力下降;运动与限食干预对肥胖大鼠股骨抗变形能力有交互作用。

Effect of Exercise and Caloric Restriction on the Density and Biomechanical Propenies of Femoral Bone in Obese Rats

Objective This study was carried out to investigate the effects of exercise and caloric restriction on the density and biomechanical properties of bone in obese rats. Methods Thirty two obese rats were randomly devided into 4 groups: caloric restriction group (CR)(n=7),regular exercise group (EX)(n=9),caloric restriction plus exercise group(n=9),and control group(n=7). All rats were continueously fed with high fat diet, except the rats in CR group (only 80% of mean daily intake of control rats). Body weight and Lee’s index was measured and calculated weekly. Rats in EX group swam 90 minutes per day, 6 day per week, for a total of 5 weeks. All rats were killed 60 hours after the last exercise, and weight and Lee’s index were detected, and femural bones of rats were removed and stored at 4℃ . Bone density examination and biomechanical testing were performed within following 24 hours. Results ① Weight of the obese SD rats in CR or EX group reduced significantly(P <0.01)without significant interaction between two groups(P >0.05). ② There were no significantly changes in the length and volumetric density of the femurs(P>0.05)in CR or EX groups. ③ The maximum load,elastic load and general energy absorption of the femur in CR group were lower then in control group (P<0.01)and there was an interaction between EX and CR groups (P<0.01). Conclusion ① Caloric restriction and regular exercise significantly reduced the weight of the obese SD rats,while did not affect the the length and volumetric densitometer of the obese rat’s femur in a relatively shorter period of time. ② Caloric restriction alone reduced the hardness, fracture resistance and deformation resistance of the obese rat’s femur, and there was an interaction of deformation resistance of the femur between EX and CR.