Glatt Vaida, Canalis Ernesto, Stadmeyer Lisa, Bouxsein Mary L
Orthopedic Biomechanics Laboratory, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
J Bone Miner Res. 2007 Aug;22(8):1197-207. doi: 10.1359/jbmr.070507.
We used microCT and histomorphometry to assess age-related changes in bone architecture in male and female C57BL/6J mice. Deterioration in vertebral and femoral trabecular microarchitecture begins early, continues throughout life, is more pronounced at the femoral metaphysis than in the vertebrae, and is greater in females than males.
Despite widespread use of mice in the study of musculoskeletal disease, the age-related changes in murine bone structure and the relationship to whole body BMD changes are not well characterized. Thus, we assessed age-related changes in body composition, whole body BMD, and trabecular and cortical microarchitecture at axial and appendicular sites in mice.
Peripheral DXA was used to assess body composition and whole body BMD in vivo, and microCT and histomorphometry were used to measure trabecular and cortical architecture in excised femora, tibia, and vertebrae in male and female C57BL/6J mice at eight time-points between 1 and 20 mo of age (n = 6-9/group).
Body weight and total body BMD increased with age in male and female, with a marked increase in body fat between 6 and 12 mo of age. In contrast, trabecular bone volume (BV/TV) was greatest at 6-8 wk of age and declined steadily thereafter, particularly in the metaphyseal region of long bones. Age-related declines in BV/TV were greater in female than male. Trabecular bone loss was characterized by a rapid decrease in trabecular number between 2 and 6 mo of age, and a more gradual decline thereafter, whereas trabecular thickness increased slowly over life. Cortical thickness increased markedly from 1 to 3 mo of age and was maintained or slightly decreased thereafter.
In C57BL/6J mice, despite increasing body weight and total body BMD, age-related declines in vertebral and distal femoral trabecular bone volume occur early and continue throughout life and are more pronounced in females than males. Awareness of these age-related changed in bone morphology are critical for interpreting the skeletal response to pharmacologic interventions or genetic manipulation in mice.
我们使用显微CT和组织形态计量学来评估雄性和雌性C57BL/6J小鼠骨骼结构的年龄相关变化。椎体和股骨小梁微结构的退化在早期就开始了，贯穿一生，在股骨干骺端比在椎体更明显，并且在雌性中比在雄性中更严重。
尽管小鼠在肌肉骨骼疾病研究中被广泛使用，但小鼠骨骼结构的年龄相关变化以及与全身骨密度变化的关系尚未得到很好的描述。因此，我们评估了小鼠身体成分、全身骨密度以及轴向和附属部位小梁和皮质微结构的年龄相关变化。
使用外周双能X线吸收法（DXA）在体内评估身体成分和全身骨密度，并使用显微CT和组织形态计量学在1至20月龄的八个时间点测量雄性和雌性C57BL/6J小鼠切除的股骨、胫骨和椎体中的小梁和皮质结构（每组n = 6 - 9）。
雄性和雌性小鼠的体重和全身骨密度随年龄增加，在6至12月龄时体脂显著增加。相比之下，小梁骨体积（BV/TV）在6 - 8周龄时最大，此后稳步下降，特别是在长骨的干骺端区域。BV/TV的年龄相关下降在雌性中比在雄性中更大。小梁骨丢失的特征是在2至6月龄时小梁数量迅速减少，此后逐渐下降，而小梁厚度在一生中缓慢增加。皮质厚度在1至3月龄时显著增加，此后保持或略有下降。
在C57BL/6J小鼠中，尽管体重和全身骨密度增加，但椎体和股骨远端小梁骨体积的年龄相关下降在早期就开始了，贯穿一生，并且在雌性中比在雄性中更明显。了解这些与年龄相关的骨骼形态变化对于解释小鼠对药物干预或基因操作的骨骼反应至关重要。
