Stimulatory effect of puerarin on bone formation through activation of PI3K/Akt pathway in rat calvaria osteoblasts

Puerarin, a natural isoflavonoid found in Chinese Pueraria lobata (Wild.) Ohwi, has received increasing attention because of its possible role in the prevention of osteoporosis. However, the relationship between puerarin and bone formation remains unknown. In the present study, rat osteoblasts isolated from newborn Wistar rats were used to investigate the effect of puerarin on osteoblasts, and its possible molecular mechanism. Data showed that puerarin caused a significant increase in cell viability, alkaline phosphatase (ALP) activity and mineral nodules formation in osteoblasts, suggesting that puerarin had a stimulatory effect on osteoblastic bone formation. This functional improvement by puerarin was accompanied by activation and nuclear translocation of Akt. Furthermore, puerarin-stimulated osteoblastic growth, Akt activation and redistribution were significantly blocked by the specific PI3K inhibitor, LY294002. These results strongly suggested that puerarin stimulated osteoblastic proliferation and Akt activation in a PI3K-dependent manner. In summary, puerarin derived from Chinese Pueraria lobata (Wild.) Ohwi can promote bone formation in cultured rat osteoblasts, which might be mediated by activation of the PI3K/Akt pathway. DMEM:Dulbecco's modification of Eagel's medium PBS:phosphate buffered saline DMSO:dimethyl sulfoxide EDTA:ethylene diamine tetraacetic acid SDS:sodium dodecyl sulfate SDS-PAGE:sodium dodecylsulfate polyacrylamide gel electrophoresis FITC:fluorescein isothiocyanate HRP:horseradish peroxidase PI3K:phosphatidylinositol 3-kinase.