中文摘要：

目的 探讨雌激素缺乏对骨组织结构和纳米力学材料特性的影响。方法将20只10月龄SD雌性大鼠随机分为去卵巢组和假手术组，每组10只。手术后15周处死，处死前用双能X线吸收仪测量活体全身骨密度和第6腰椎骨密度。处死后测量离体的第6腰椎骨密度，取右侧胫骨近干骺端进行骨组织形态计量学检测；每组随机选取3个椎体，甲基丙烯酸甲酯包埋后，将椎体沿长轴中点垂直长轴锯开，暴露横断面骨小梁，取下半段表面打磨，随机选取4处骨小梁，每处骨小梁选取5个点进行纳米压痕实验。结果大鼠去卵巢后15周，第6腰椎骨密度显著降低；胫骨骨小梁间隔明显增宽，骨小梁体积分数显著下降（P〈0．05）。全身骨密度、骨小梁数量及骨小梁厚度呈下降趋势。纳米压痕实验测得的去卵巢组和假手术组椎体骨小梁硬度分别为0.91GPa±0．13GPa和0．90GPa±0.09GPa，弹性模量分别为21.01GPa±2，48GPa和22．04GPa±2．44GPa，两组间差异无统计学意义。结论纳米压痕技术是一项可用于直接测量骨组织纳米力学特性的新技术。去卵巢雌激素缺乏虽引起骨质疏松，但对骨小梁的纳米力学性能无明显影响。

英文摘要：

Objective To study the nanomechanical properties of the vertebral trabeculae of ovarectomized rat using nanoindentation. Methods Twenty 10-month-old SD rats were randomly divided into 2 equal groups： ovariectomized （OVX） group and Sham operation （SHAM） group. Fifteen weeks postoperationally dual energy X-ray absorptiometry was used to measure the bone mineral density （BMD） of the total body and of the sixth lumbar vertebra. Then the rats were killed. The BMD values of the sixth lumbar vertebrae were measured by DXA. Bone histomorphometry was performed on the proximal metaphysis of the right tibia. Three of the sixth lumbar vertebrae were randomly selected from each group and embedded in methyl methacrylate. Each vertebra was cut into two parts along the transverse direction in the middle point of longitudinal axis so as to expose the trabeculae on the cross section. The lower part was polished, trabeculae were randomly selected from 4 places, and 5 points from each place were randomly selected to undergo nanoindentation so as to measure the nanomechanical properties. Results Compared with the SHAM rats, the BMD of the sixth lumbar vertebra of the OVX rats was reduced significantly （ P 〈 0.05 ）. The histomorphometry of the tibia showed an increase in trabecular separation and a decrease in trabecular bone area fraction （ both P 〈 0. 05） ; the trabecular number and thickness decreased in these 2 groups, however, without significant difference between them. Nanoindentation tests showed that the values of hardness and elastic modulus of the trabeculae of the OVX rats were 0.91 GPa ±0. 13 GPa and 21.01 GPa ± 2.48 GPa respectively, not significantly different from those of the SHAM rats, 0.90 GPa ±0.09 GPa and 22.03 GPa ± 2.44 GPa respectively. Conclusion A novel technique, nanoindentation is able to directly measure the nanomechanical properties of trabeculae. Estrogen deficiency after ovariectomy induces significant osteoporotic change, but has no significant influence on the trabecular