去卵巢大鼠胫骨和椎骨松质骨微结构的显微CT分析

摘要

目的 观察大鼠去卵巢后,椎骨和胫骨松质骨微结构变化.方法 50只7月龄SD大鼠随机分为基线组,去卵巢组和假手术组.基线组在试验开始时处死,去卵巢组和假手术组分别在去卵巢后3周、15周各处死.分离大鼠第五腰椎和左侧胫骨,用显微CT( microCT)对椎骨及胫骨骨骺端松质骨进行扫描,对其微结构定量分析.结果 去卵巢第3周和第15周,OVX组胫骨骨体积分数(BV/TV)、骨小梁数量(Tb.N)和连接密度(Conn.D)均显著性小于SHAM组,骨小梁间隔(Tb.Sp)和结构模型指数(SMI)均明显大于SHAM组.去卵巢第3周,OVX组椎骨BV/TV显著性小于SHAM组,SMI明显大于SHAM组,至第15周,OVX、SHAM两组间椎骨的微结构差异与胫骨相同.纵向观察,OVX组胫骨随着时间变化出现BV/TV和Conn.D进行性减少,Tb.Sp进行性增加,面积骨密度(tBMD)和骨小梁厚度(Tb.Th)在第3到15周分别出现下降和增加.OVX组椎骨BV/TV在去卵巢3周内下降,Conn.D和Tb.Sp在3到15周内分别出现减少和增加.胫骨和椎骨的Tb.N随时间均进行性减少,SMI均在3周内增加.结论 雌激素缺乏时大鼠松质骨微结构改变呈现出区域性,胫骨松质骨微结构丢失的发生比椎骨早,更为显著.%Objective To observe the change of trabecular microstructure of the tibia and vertebrae in rats after ovariectomy. Methods Fifty seven-month-old rats were divided into baseline, OVX(ovariectomized) , and SHAM ( Sham-operated) groups. Rats in baseline group were executed at the beginning of the study. Rats in OVX and SHAM group were executed at 3 weeks and IS weeks after ovariectomy, respectively. The fifth lumber and the left tibia were separated and harvested. The trabeculae in the vertebrae and proximal metaphysics of tibia were scanned using micro-CT to analyze the microstructure quantitatively. Results At the 3rd and 15th week after surgery, trabecular bone volume ( BV/TV ) , trabecular number (Tb. N ) , and trabecular connectivity density ( Conn. D) of rats in OVX group were significantly lower than those in SHAM group. However, trabecular separation ( Tb. Sp) and structural model index (SMI) were significantly larger than those in SHAM group. At 3 weeks after surgery, BV/TV of rats in OVX group was significantly lower than that in SHAM group, but SMI of rats in OVX group was higher than that in SHAM group. At the 15 weeks after surgery, the difference of vertebral microstructure between OVX and SHAM group was similar to that of the tibia. When observed longitudinally, BV/TV and Conn. D of the tibias in rats of OVX group gradually decreased along with time, while Tb. Sp increased.tBMD and Tb. Th decreased at 3 weeks but increased at 15 weeks after the surgery. BV/TV of the vertebrae in rats of OVX group decreased at 3 weeks after the surgery. Conn. D and Tb. Sp decreased at 3 weeks but increased at 15 weeks after the surgery. Tb. N of the tibia and vertebrae gradually decreased along with time. SMI increased in 3 weeks. Conclusion The change of trabecular bone microstructure appears to be site-specific in estrogen deficient rats. The microstructure deterioration of trabecular bone in the tibia happens earlier and severer than in the vertebrae.