DeSouza R, Javaheri B, Collinson R S, Chenu C, Shefelbine S J, Lee P D, Pitsillides A A
Universidade Federal de Mato Grosso (UFMT) - Departamento de Clínica, Cuiabá, Brazil.
J Musculoskelet Neuronal Interact. 2017 Sep 1;17(3):218-225.
Short-term neurectomy-induced disuse (SN) has been shown to restore load responses in aged mice. We examined whether this restoration was further enhanced in both cortical and trabecular bone by simply extending the SN.
Following load:strain calibration, tibiae in female C57BL/J6 mice at 8, 14 and 20 weeks and 18 months (n=8/group) were loaded and bone changes measured. Effects of long-term SN examined in twenty-six 18 months-old mice, neurectomised for 5 or 100 days with/without subsequent loading. Cortical and trabecular responses were measured histomorphometrically or by micro-computed tomography.
Loading increased new cortical bone formation, elevating cross-sectional area in 8, 14 and 20 week-old (p ⟨0.05), but not 18 month-old aged mice. Histomorphometry showed that short-term SN reinstated load-responses in aged mice, with significant 33% and 117% increases in bone accrual at 47% and 37%, but not 27% of tibia length. Cortical responses to loading was heightened and widespread, now evident at all locations, following prolonged SN (108, 167 and 98% at 47, 37 and 27% of tibial length, respectively). In contrast, loading failed to modify trabecular bone mass or architecture.
Mechanoadaptation become deficient with ageing and prolonging disuse amplifies this response in cortical but not trabecular bone.
短期神经切除术诱导的废用（SN）已被证明可恢复老年小鼠的负荷反应。我们研究了通过简单延长SN时间，这种恢复在皮质骨和小梁骨中是否会进一步增强。
在进行负荷-应变校准后，对8周、14周、20周和18个月大的雌性C57BL/J6小鼠（每组n = 8）的胫骨进行加载，并测量骨变化。在26只18个月大的小鼠中研究长期SN的影响，这些小鼠接受5天或100天的神经切除术，术后进行或不进行加载。通过组织形态计量学或微计算机断层扫描测量皮质骨和小梁骨的反应。
加载增加了新皮质骨的形成，使8周、14周和20周龄小鼠的横截面积增加（p＜0.05），但18个月龄的老年小鼠没有增加。组织形态计量学显示，短期SN恢复了老年小鼠的负荷反应，在胫骨长度的47%和37%处骨量分别显著增加33%和117%，但在27%处没有增加。在延长SN时间后（分别在胫骨长度的47%、37%和27%处增加108%、167%和98%），皮质骨对加载的反应增强且广泛，现在在所有位置都很明显。相比之下，加载未能改变小梁骨的质量或结构。
机械适应性会随着衰老而不足，延长废用时间会放大皮质骨而非小梁骨的这种反应。
