Location: Arkansas Children's Nutrition CenterTitle: Feeding blueberry diets dose-dependently inhibits bone resorption in young rats Author
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2011
Publication Date: 4/1/2012
Citation: Zhang, J., Lazarenko, O.P., Blackburn, M.L., Badger, T.M., Ronis, M.J., Chen, J. 2012. Feeding blueberry diets dose-dependently inhibits bone resorption in young rats. The Federation of American Societies for Experimental Biology Journal. 26 (Meeting Abstract):244.5. Interpretive Summary: It has been recognized that eating appropriate nutrition in early life is one of the critical factors that influences bone development. Our previous studies demonstrated that consumption of BB early in life is a benefit for the bone mass accretion. Weanling rats fed diets supplemented with 10% whole blueberry (BB) powder for only two weeks beginning on postnatal day 21 (PND21) significantly promoted bone formation. In this report, we examined the effect of three lower concentration of BB diet supplementation (1, 3, and 5%) on bone development. The result of CT scan of long bones showed bone quality significantly increased in BB fed rats compared with animals with control diets. Interestingly, this effect was dose-dependent. Increased bone quality with blueberry diet was associated with a decreasing the differentiation of bone resorption cells called osteoclasts. The osteoclasts differentiation protein marker RANKL (the cytokine receptor activator of nuclear factor-'B ligand essential for osteoclast formation) was dose-dependently decreased in BB fed animals. Furthermore, some other bone resorption related genes, PPAR', RANKL and TRAP, were down-regulated by BB diets. These observations suggest that BB consumption during early development could stimulate bone development by inhibition of bone resorption with a dose-dependent manner.
Technical Abstract: Nutritional status is a critical factor that influences bone development. We previously reported that weanling rats fed AIN-93G semi-purified diets supplemented with 10% whole blueberry (BB) powder for only two weeks beginning on postnatal day 21 (PND21) significantly promoted bone formation. However, whether there is an effect of BB diet on bone at lower levels of supplementation or if there are additional effects on bone resorption is unknown. The current study examined the effects of three levels of BB diet supplementation (1, 3, and 5%) for 14 days beginning on PND21on osteoclastic bone resorption. Using peripheral quantitative CT scan of tibia, we demonstrated that bone mineral density and content were dose-dependently increased in BB rats compared to control AIN-93G fed animals (p < 0.05). Proteins were isolated from long bone of femurs, and Western blot revealed that RANKL (the cytokine receptor activator of nuclear factor-'B ligand essential for osteoclast formation) protein expression was dose-dependently decreased (p<0.05). This was accompanied by decreased expression of PPAR', RANKL and TRAP (Tartrate-resistant acid phosphatase) mRNA expression (p<0.05). These results indicate significant stimulation of bone growth by dose-dependent inhibition of bone resorption after BB consumption during early development.