Abstract
Previous studies have demonstrated that weanling rats fed AIN-93G semi-purified diets supplemented with 10% whole blueberry (BB) powder for two weeks beginning on postnatal day 21 (PND21) significantly increased bone formation at PND35. However, the minimal level of dietary BB needed to produce these effects is, as yet, unknown. The current study examined the effects of three different levels of BB diet supplementation (1, 3, and 5%) for 35 days beginning on PND25 on bone quality, and osteoclastic bone resorption in female rats. Peripheral quantitative CT scan (pQCT) of tibia, demonstrated that bone mineral density (BMD) and content (BMC) were dose-dependently increased in BB-fed rats compared to controls (P<0.05). Significantly increased bone mass after feeding 5% BB extracts was also observed in a TEN (total enteral nutrition) rat model in which daily caloric and food intake was precisely controlled. Expression of RANKL (receptor activator of nuclear factor-κB ligand) a protein essential for osteoclast formation was dose-dependently decreased in the femur of BB animals. In addition, expression of PPARγ (peroxisome proliferator-activated receptor γ) which regulates bone marrow adipogenesis was suppressed in BB diet rats compared to non-BB diet controls. Finally, a set of in vitro cell cultures revealed that the inhibitory effect of BB diet rat serum on RANKL expression was more profound in mesenchymal stromal cells compared to its effect on mature osteoblasts, pre-adipocytes and osteocytes. These results suggest that inhibition of bone resorption may contribute to increased bone mass during early development after BB consumption.
Highlights
Bone development is largely influenced by nutritional status, dietary factors, body composition and the effects of weight bearing/physical activity [1]; [2]
We have presented novel data suggesting consumption of a BBcontaining diet was able to suppress bone resorption through down-regulation of RANKL in stromal cells and/or PPARc in pre-adipocytes
It has been suggested that a 10% BB in the diet in early life has a positive effect on protection against bone loss after ovariectomy in adult female rats [29]
Summary
Bone development is largely influenced by nutritional status, dietary factors, body composition and the effects of weight bearing/physical activity [1]; [2]. The human diet contains a complex array of factors including phytochemicals that interact with specific genes that may be essential for bone development. It is known that fruits and vegetables are rich in phytochemicals, such as phenolic acids, flavonoids and isoflavones previously shown to be bone anabolic [3]. We have recently characterized a 10% blueberry (BB)-supplemented diet that had significant effects to promote osteoblastic bone formation in intact young male and female rats [6]. This bone anabolic effect of BB diet was suggested to be due to stimulation of osteoblastic differentiation caused by phenolic acid metabolites derived from BB polyphenols [6]. We hypothesize that BB diet has an inhibitory effect on osteoclastic bone resorption and this may contribute to the significant increases in bone mass in rapidly growing rats associated with this diet
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call