Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis)
Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis)
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DOI：
10.1016/j.bone.2007.10.010
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发表时间：
2008-02-01
期刊：
影响因子：
4.1
通讯作者：
Donahue, Seth W.
中科院分区：
文献类型：
--
作者：
Mcgee, Meghan E.;Maki, Aaron J.;Donahue, Seth W.
废用使骨形成与再吸收分离，导致孔隙率增加、骨几何性质降低和骨矿物质含量降低，这损害骨机械性质并增加骨折风险。然而，黑熊骨的特性并没有受到老化的不利影响，尽管每年都有废弃期（即，冬眠），这表明熊要么在废用期间防止骨质流失，要么失去骨骼，随后以比其他动物更快的速度恢复。在这里，我们显示减少皮质骨营业额在冬眠期间与平衡的形成和吸收灰熊股骨。冬眠灰熊股骨的多孔性更少，矿化程度更高，与活动灰熊股骨相比，皮质骨几何形状或全骨机械性能未发生任何变化。在冬眠期间皮质重塑的激活频率比体力活动期间低75%，但标准化的矿物质沉积率不变。这些数据表明，在冬眠期间骨转换减少，但骨单位继续以正常速率重新填充。冬眠熊股骨的孔隙度，几何形状或重塑指数的区域变化没有变化，表明冬眠并没有优先影响皮质的一个区域。因此，灰熊通过减少骨转换和保持平衡的形成和再吸收来防止废用期间的骨丢失，从而保护骨结构和强度。这些结果支持熊具有防止废用性骨质疏松症的生物学机制的观点。(c)2007年爱思唯尔公司All rights reserved.
Disuse uncouples bone formation from resorption, leading to increased porosity, decreased bone geometrical properties, and decreased bone mineral content which compromises bone mechanical properties and increases fracture risk. However, black bear bone properties are not adversely affected by aging despite annual periods of disuse (i.e., hibernation), which suggests that bears either prevent bone loss during disuse or lose bone and subsequently recover it at a faster rate than other animals. Here we show decreased cortical bone turnover during hibernation with balanced formation and resorption in grizzly bear femurs. Hibernating grizzly bear femurs were less porous and more mineralized, and did not demonstrate any changes in cortical bone geometry or whole bone mechanical properties compared to active grizzly bear femurs. The activation frequency of intracortical remodeling was 75% lower during hibernation than during periods of physical activity, but the normalized mineral apposition rate was unchanged. These data indicate that bone turnover decreases during hibernation, but osteons continue to refill at normal rates. There were no changes in regional variation of porosity, geometry, or remodeling indices in femurs from hibernating bears, indicating that hibernation did not preferentially affect one region of the cortex. Thus, grizzly bears prevent bone loss during disuse by decreasing bone turnover and maintaining balanced formation and resorption, which preserves bone structure and strength. These results support the idea that bears possess a biological mechanism to prevent disuse osteoporosis. (c) 2007 Elsevier Inc. All rights reserved.