骨微破裂评价去卵巢大鼠骨结构与质量作用

目的 :比较微破裂与骨密度、骨生物力学和骨形态计量指标 ,探讨微破裂作为骨结构性能评价的可能性。方法 :8只 10月龄SD大鼠于实验开始时处死作为基础对照 ,90只随机分成A ,B ,C 3组 ,每组包括去卵巢组 (OVX组 )、17β 雌二醇替代组 (EST组 )和对照组 (SHAM组 ) 3种处理组 ,3组大鼠分别于去卵巢后 3周、15周和2 1周处死。处死前进行全身骨和腰椎骨骨密度测定 ;处死后进行离体腰椎骨和胫骨骨密度测定。右侧胫骨上端行常规骨形态计量学测量 ;取离体第五腰椎体进行椎体压缩实验 ;对离体第四腰椎体进行疲劳损伤试验 ,大块组织碱性品红染色后制成骨磨片 ,测量微破裂密度和表面密度。观察不同时期、不同处理组之间的各种指标的变化差别。结果 :① 15周和 2 1周时 ,多个部位的骨密度、微破裂表面密度及微破裂密度大于 3周时的测量值。② 15周时 ,骨小梁间隔增加 ,骨小梁数目减少 ,椎体最大载荷和椎体弹性模量达到峰值。③ 3周时 ,OVX组的骨小梁间隔大于EST组 ,骨小梁面积百分率小于EST组和SHAM组 ,OVX组微破裂表面密度及微破裂密度大于EST组 ,但 3种处理组之间骨密度指标及力学指标无明显改变。④ 15周时 ,OVX组和EST组多处骨密度和椎体最大载荷低于SHAM组 ,但骨形态计量学指标、微破裂指标和椎体弹性模量无明

Evaluation of bone structure and quality of ovariectomized rats by microcrack

Objective To compare microcrack with bone mineral desity (BMD),bone histomorphometry and biomechanics parameters, and to investigate the potential of microcrack in the evaluation of bone biomechanical quality. Methods Eight 10-month-old Sprague-Dawley rats were served as baseline controls, and 90 10-month-old rats were randomly divided into A, B, and C groups. Each group comprised ovariectomized (OVX),17 β-estradiol treated EST,10 μg/(kg·d)] and sham-operated (SHAM) subgroups. Rats from groups A,B and C were killed at the 3rd, 15th and 21st week post-operatively. Total body and lumbar vertebral BMD were measured before being killed,and BMD of isolated lumbar vertebrae and tibiae were measured after killing. Bone histomorphometry of the proximal end of isolated right tibia was performed,and compression test was carried out on the isolated 5th lumbar vertebra (L 5). After fatigue damage, the isolated 4th lumbar vertebra was stained by en bloc basic fuchsin staining, and microcrack density (Cr.Dn) and microcrack surface density (Cr.SDn) were determined on the bone tissue sections. Bone parameters in each subgroup of rats were observed at different time. Results ①At the 15th and 21st week post-operatively, multi-part BMD, Cr.Dn and Cr.SDn were higher than those at the 3rd week. ②At the 15th week, trabecular separation (Tb.Sp) increased,trabecular number (Tb. N) decreased, and the maximum loading level and elastic modulus of vertebra reached the peak. ③At the 3rd week, Tb. Sp, Cr.Dn and Cr.SDn in the OVX subgroup were greater than those in the EST subgroup, while the percentage of trabecular area (TbTr) in the OVX subgroup was lower than that of the EST and SHAM subgroups. No changes of BMDs and biomechanic parameters were observed among the three subgroups. ④At the 15th week, multi-part BMD and maximum loading level in the OVX and EST subgroups were lower than those in the SHAM subgroup, while elastic modulus, bone histomorphometry parameters, Cr.Dn and Cr.SDn had no change among the three subgroups. ⑤At the 21st week,multi-part BMDs, Tb. N and TbTr in the OVX subgroup were smaller than those in the EST and SHAM subgroups. Tb. Sp, bone formation rate,mineral apposition rate, percent labeled perimeter,Cr.Dn and Cr.SDn in the OVX subgroups were greater than those in the EST and SHAM subgroups. Maximum loading level and elastic modulus of vertebra in EST and OVX subgroups were lower than those in the SHAM subgroup. There were no significant differences in all of these parameters between the EST and the SHAM subgroup. Conclusion Microcrack can be regarded as an alterative parameter in the evaluation of bone biomechanical quality.