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United States Department of Agriculture

Agricultural Research Service

Title: Obesity induced by high dietary fat leads to increased bone resorption marker, TRAP, and decreased bone mass in mice)

Author
item Cao, Jay
item Gregoire, Brian
item Gao, Hongwei

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2008
Publication Date: 8/12/2008
Citation: Cao, J.J., Gregoire, B.R., Gao, H. 2008. Obesity induced by high dietary fat leads to increased bone resorption marker, TRAP, and decreased bone mass in mice [Abstract]. 23S1:432.

Interpretive Summary:

Technical Abstract: Obesity, which is growing in prevalence, is a risk factor for such chronic health disorders as diabetes and cardiovascular diseases. However, it is thought to be a protective factor for osteoporosis and bone fractures in humans. Accumulating data in humans suggest that fat mass has a negative effect on bone when the confounding factor, mechanical loading of body weight in obesity, was removed. Furthermore, obesity is associated with the chronic up-regulation of inflammatory cytokines such as TNF-a, IL-1ß, IL-6, and IL-7. These cytokines have been shown to be capable of stimulating osteoclast activity and bone resorption through regulating the RANKL/RANK/OPG pathway. To determine how dietary fat might affect bone metabolism, we examined in vitro bone formation, blood markers of bone homeostasis, and bone structure in male C57BL/6 mice fed either a high-fat diet (HFD, 45% kcal as fat) or a normal fat control diet (NFD, 10%) for 14 weeks starting at 6 wk of age. Cancellous bone volume/total volume ratio decreased (P<0.05) in mice fed the HFD despite a greater average body weight (10 g) than those fed the NFD (P<0.01). Compared with mice fed the NFD, the numbers of colony forming units (CFU)-fibroblastic and CFU-alkaline phosphatase positive at d 14 and mineralization nodule at d 28 were higher in bone marrow stromal cells from mice fed the HFD. Serum osteocalcin was lower (P<0.05) with HFD as compared to NFD (71.2±11.7 vs 53.4±17.0 for NFD and HFD groups, respectively). Serum TRAP and OPG levels were higher in the HFD mice when compared to the NFD mice (TRAP: 1.74±0.33 vs 2.54±1.03 U/L; OPG: 1.39±0.58 vs 2.81±2.09ng/ml, for NFD and HFD diet respectively). No significant differences were observed between the two groups for serum RANKL (3.07±2.30 vs 3.87±2.52 nmol/ml for NFD and HFD, respectively). Taken together, our data suggest that a HFD results in elevated bone resorption that exceeds increased bone formation and obesity induced by high fat intake is detrimental to bone structure.

Last Modified: 8/24/2016
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