^(99)Tc-亚甲基二膦酸盐对糖皮质激素诱导的骨质疏松大鼠胫骨微结构的影响

Effects of ^(99)Tc-MDP on tibial microarchitecture of glucocorticoid-induced osteoporotic rats

目的:应用显微CT研究不同剂量的99Tc-亚甲基二膦酸盐(MDP)对糖皮质激素诱导的骨质疏松大鼠胫骨微结构的影响。方法:48只大鼠随机分为6组:空白组,阴性对照组,大、中、小剂量组和阳性对照组。诱导:除空白组,其余各组给予地塞米松。治疗:大、中、小剂量组分别予10mg/kg、5mg/kg、2.5mg/kg99Tc-MDP,阳性对照组给予5mg/kgMDP。实验结束处死大鼠,剥离右侧胫骨行显微CT扫描,比较分析各组松质骨的骨体积/总体积(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)、骨小梁分离度(Tb.Sp)和皮质骨厚度(Ct.Th)。结果:与空白组相比,阴性对照组松质骨BV/TV、Tb.N降低,Tb.Sp升高(P<0.05);小剂量组和阴性对照组相比,BV/TV、Tb.N升高,Tb.Sp降低(P<0.05);中、大剂量组和阳性对照组,与阴性对照组相比,4项松质骨参数均有改善(P<0.05)。与空白组相比,阴性对照组Ct.Th降低(P<0.01);99Tc-MDP各剂量组与阴性对照组相比,Ct.Th均升高(P<0.01)。结论:99Tc-MDP能够干预糖皮质激素诱导的大鼠骨微结构的改变,小剂量即有效,作用随剂量增加而增加;99Tc-MDP对皮质骨厚度的改善明显优于MDP。

Objective：To study the effects of different doses of 99Tc-MDP（99Technetium-methylene diphosphonate） on the tibial microarchitecture of glucocorticoid-induced osteoporotic（GIOP） rats by micro-CT.Methods：Forty-eight rats were randomly divided into six groups：blank group,negative control group,high dose group,medium dose group,low dose group and positive control group.During the induction period,dexamethasone was given to all five groups except blank group.In the treatment period,10mg/kg,5mg/kg and 2.5mg/kg 99Tc-MDP were given to high dose,medium dose and low dose groups respectively,and positive control group was given 5mg/kg MDP（methylene diphosphonate）.All rats were sacrificed,with their right tibiae scanned and analyzed by micro-CT.Results：①Cancellous bone：compared to the blank group,rats in the negative control group had decreased bone volume/total volume（BV/TV） and trabecular number（Tb.N）as well as increased trabecular spacing（Tb.Sp）（P0.05）;compared to the negative control group,rats in the low dose group had increased BV/TV and Tb.N,and decreased Tb.Sp（P0.05）;for medium dose,high dose and positive control groups,all four cancellous parameters improved after treatment（P0.05）.②Cortical bone：cortical thickness（Ct.Th）decreased in the negative control group in contrast to the blank group（P0.01）;Ct.Th in all three 99Tc-MDP groups increased comparing to the negative group（P0.01）.Conclusion：99Tc-MDP can improve the glucocorticoid-induced microarchitecture changes in rat bones,low dose is effective and the efficacy improves as dose increases.Comparing to MDP,99Tc-MDP excels in improving cortical thickness.