间断性水平位站立对尾吊大鼠胫骨骨小梁结构影响的micro-CT评价

Evaluation of the effect of intermittent standing exposure on the tibia trabecular structure in tail-suspended rats using micro-CT

目的应用micro-CT研究尾吊大鼠胫骨骨小梁微结构的变化,以此评价间断性水平位站立对抗模拟失重导致的骨微结构退化的效果。方法 24只SD雄性大鼠随机等分为3组:对照组(CON组)、尾吊组(SUS组)、水平位站立对抗组(ST组)。尾吊组大鼠始终保持约30°头低位及后肢自由悬垂不负重状态,水平位站立对抗组在尾吊处理的基础上,大鼠每天固定时间水平站立1 h。实验3周后处死各组大鼠,取其右侧胫骨行micro CT扫描及三维重建,对其骨微结构进行定量分析。结果选定感兴趣区(ROI)行定量分析及三维可视化后,与CON组相比,SUS组胫骨骨体积分数(BVF)、骨小梁数量(Tb.N)、骨小梁厚度(Tb.Th)均显著降低,而骨表面积/体积(BS/BV)、骨小梁间隙(Tb.Sp)及骨小梁模式因子(Trabecular Pattern Factor,TPF)均显著升高;ST组的变化介于SUS组和CON组之间;三维可视化图像结果与物理参数结果趋势一致。应用One-Way ANOVA分析及多重比较LSD-t检验,三组各参数之间统计学差异显著(P<0.05)。结论间断性水平位站立可明显减弱尾吊大鼠胫骨的微结构退化和骨质丢失,而micro CT可以有效地辨别胫骨松质骨微结构的精细变化。

Objective To study the changes of the tibia trabecular microstructure in tail-suspended rats using micro CT, in order to evaluate the effect of intermittent standing exposure on mierostructure degeneration induced by hind limp unloading. Methods Twenty-four male Sprague-Dawley rats were randomly and equally divided into 3 groups： control group （CON） , suspension group （SUS） , and intermittent standing group （ST）. The tail-suspended rats were kept approximately 30~ head-down-tilt and tail-suspension for 3 weeks, and the rats in intermittent standing group were granted hind limb reloading for 1 hour per day at fixed time on the basis of tail-suspension. After 3-week treatment, all the rats were euthanized, and the right tibias were collected for miero-CT scanning and three-dimensional reconstruction. Quantitative analysis of bone microstructure was also performed. Results Quantitative analysis and three-dimensional visualization of the region of interest （ROI） were performed. The results showed that bone volume fraction （BVF） , trabecular number （Tb. N） , and trabecular thickness （Tb. Th） in SUS group were significantly lower than those in CON group. While bone surface area/bone volume （BS/BV）, trabecular separation （Tb. Sp ）, and trabecular pattern factor （TPF） were significantly higher than those in latter group. The changes in ST group were between these 2 groups. Three-dimensional visualized image showed similar trends with the physical parameters. Statistical analysis was performed using One-wayANOVA analysis and LSD-t multiple comparison. No significant difference among the three groups was observed （P 〈 0.05 ）. Conclusion Intermittent standing resistance can significantly alleviate microstructure degeneration and bone loss of the tibia induced by tail-suspension. And meticulous changes of the tibia trabecular microstructure can be detected and distinguished by micro-CT.