糖皮质激素对大鼠胫骨松质骨密度和微结构的动态影响

目的 应用显微CT研究糖皮质激素(GC)随时间延长对大鼠胫骨松质骨密度和微结构的影响.方法 52只3.5个月龄雌性SD大鼠随机分为基线组10只、糖皮质激素造模组(GCT)22只和对照组20只.基线组10只实验开始时即处死,GCT组和对照组分别在实验开始后1周、9周各处死11只和10只,分别保存右侧胫骨,行显微CT扫描,并在扫描完成后,进行三维重建,获取骨小梁三维结构图像,最后进行松质骨定量分析.结果 GCT组的体积骨密度(vBMD)、组织骨密度(tBMD)、骨体积分数(BVF)、骨小梁数量(Tb.N)、各向异性度(DA)和骨小梁连接密度(Conn.D)较对照组下降,9周时,改变更显著(均P<0.05),而骨小梁厚度(Tb.Th)、骨小梁间隔(Tb.Sp)和结构模型指数(SMI)较对照组升高;GCT组随造模时间的延长,BVF、Conn.D、Tb.N和DA进一步下降,Tb.Th和Tb.Sp显著增加(均P<0.05).GCT组1周和9周时,Tb.Th分别为(0.076±0.020)mm和(0.086±0.026)mm,高于基线组(0.067±0.014)mm,也高于对照组1周(0.075±0.022)mm和9周(0.072±0.009)mm.结论 GC可引起大鼠胫骨松质骨进行性骨量下降和骨微结构破坏,但残余的骨小梁有代偿性肥厚表现.

Dynamic effects of glucocorticoid on bone mineral density and microarchitecture: experiment with rats

Objective To investigate the Dynamic effects of glucocorticoid (GC) on bone mineral density and microarchitecture time-related changes of trabecular bone in bone mineral density (BMD) and microarchitecture in glucoeorticoid -treated rats. Methods Fifty-two 3.5-month-old female SD rats were randomly divided into 3 groups. Ten rats were killed at the beginning of experiment with their right tibiae taken out as the baseline group; 22 rats underwent subcutaneous injection of methylprednisolone once daily (GC-treated group) , and the other 20 rats underwent subcutaneous injection of normal saline once daily as control group. One and 9 weeks after the beginning of experiment 11 and 10 rats from GCT Group and control group each were killed with their right tibiae taken out. High resolution micro-CT was used to identify the densimetric and microarchitectural properties of the trabecula in the proximal metaphysic of tibia. Results Compared with the control group the values of volumetric BMD ( vBMD ), tissue BMD ( tBMD ), bone volume fraction ( BVF ) , trabecular number ( Tb. N ) , degree of anisotropy ( DA ) , and trabecular connectivity (Conn. D) in the trabecular bone at different time-points, of the GCT group all decreased; and the values in the ninth week were the lowest (all P 0. 05). The values of trabecular thickness (Tb. Th), trabecular separation (Tb. Sp), and structure model index (SMI) at different time-points of the GCT group were higher than those of the control group. A time-related analysis within the GCT group showed there was a declination in BVF, Conn. D, Tb. N, and DA with administration time, but Tb. Th and Tb. Sp were increased significantly ( all P 0. 05 ). The mean values of Tb. Th in the first week and the ninth week of GCT Group were ( 0. 076 ± 0. 020 ) mm and ( 0. 086 ± 0. 026 ) mm respectively, both higher than the baseline value (0. 067 ± 0. 014) mm] and the values of the control group in the first and ninth weeks (0. 075 ± 0. 022) mm and (0. 072 ± 0. 009) mm respectively]. Conclusion Administration of GC time-dependently decreases the BMD and causes deterioration in microarchitecture of trabecular bone; and the remaining trabeculae seem thicken to increase their strength as compensation.