Journal article
Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears ( Ursus arctos horribilis)
Bone (New York, N.Y.), Vol.42(2), pp.396-404
2008
Handle:
https://hdl.handle.net/2376/107258
PMCID: PMC2249622
PMID: 18037367
Abstract
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.
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Details
- Title
- Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears ( Ursus arctos horribilis)
- Creators
- Meghan E McGee - Department of Biomedical Engineering, Michigan Technological University, 309 Minerals and Materials Engineering Building, 1400 Townsend Drive, Houghton, MI 49931, USAAaron J Maki - Department of Biomedical Engineering, Michigan Technological University, 309 Minerals and Materials Engineering Building, 1400 Townsend Drive, Houghton, MI 49931, USASteven E Johnson - Department of Biomedical Engineering, Michigan Technological University, 309 Minerals and Materials Engineering Building, 1400 Townsend Drive, Houghton, MI 49931, USAO. Lynne Nelson - Department of Veterinary Clinical Sciences, Washington State University, USACharles T Robbins - Department of Natural Resource Sciences, Washington State University, USASeth W Donahue - Department of Biomedical Engineering, Michigan Technological University, 309 Minerals and Materials Engineering Building, 1400 Townsend Drive, Houghton, MI 49931, USA
- Publication Details
- Bone (New York, N.Y.), Vol.42(2), pp.396-404
- Academic Unit
- Environment, School of the (CAHNRS)
- Publisher
- Elsevier Inc
- Identifiers
- 99900547117101842
- Language
- English
- Resource Type
- Journal article