Sheng Zhi-feng, Dai Ru-chun, Wang Peng, Yao Xue-feng, Feng Xi-qiao, Fang Ling-Na, Fan Hui-jie, Wu Xian-ping, Liao Er-yuan
Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Changsha 410011, China.
Zhonghua Yi Xue Za Zhi. 2006 Feb 28;86(8):515-9.
To study the nanomechanical properties of the vertebral trabeculae of ovariectomized rat using nanoindentation.
Twenty 10-month-old SD rats were randomly divided into 2 equal groups: ovariectomized (OVX) group and Sham operation (SHAM) group. Fifteen weeks post-operationally 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.
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.
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 nanomechanical properties.
采用纳米压痕技术研究去卵巢大鼠椎骨小梁的纳米力学性能。
将20只10月龄SD大鼠随机分为两组，每组10只：去卵巢（OVX）组和假手术（SHAM）组。术后15周，采用双能X线吸收法测量全身及第六腰椎的骨密度（BMD）。然后处死大鼠。用双能X线吸收仪（DXA）测量第六腰椎的BMD值。对右胫骨近端干骺端进行骨组织形态计量学分析。每组随机选取3个第六腰椎，包埋于甲基丙烯酸甲酯中。沿纵轴中点将每个椎体横向切成两部分，以暴露横断面上的小梁。将下半部分抛光，从4个部位随机选取小梁，每个部位随机选取5个点进行纳米压痕，以测量纳米力学性能。
与SHAM大鼠相比，OVX大鼠第六腰椎的BMD显著降低（P<0.05）。胫骨组织形态计量学显示小梁间距增加，小梁骨面积分数降低（均P<0.05）；两组小梁数量和厚度均降低，但差异无统计学意义。纳米压痕试验显示，OVX大鼠小梁的硬度和弹性模量值分别为0.91 GPa±0.13 GPa和21.01 GPa±2.48 GPa，与SHAM大鼠的0.90 GPa±0.09 GPa和22.03 GPa±2.44 GPa相比，差异无统计学意义。
纳米压痕技术是一种能够直接测量小梁纳米力学性能的新技术。去卵巢后雌激素缺乏可引起明显的骨质疏松改变，但对小梁纳米力学性能无显著影响。
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