Puerarin promotes osteogenesis and inhibits adipogenesis in vitro

BACKGROUND: Puerarin (daidzein 8-C-glucoside) has potential on preventing osteoporosis. This study aims to investigate the effects of puerarin on osteogenesis and adipogenesis in vitro. METHODS: CCK-8 assay, alkaline phosphatase (ALP) activity and Alizarin Red S were used to measure the effects of puerarin on proliferation, osteoblastic differentiation, and mineralization in osteoblast-like MC3T3-E1 cells. The effects of puerarin on adipogenesis were measured by Oil Red O staining and intracellular triglyceride level in preadipocyte 3T3-L1 cells. The mRNA and protein levels of osteogenesis- and adiopogenesis-related factors were detected by qRT-PCR and western blot, respectively. Further, the secreted osteocalcin levels and nuclear translocation of β-catenin were detected by ELISA and immunofluorescence assay, respectively. RESULTS: As to osteogenesis, puerarin could stimulate proliferation (1 μM, P = 0.012; 10 μM, P = 0.015; 20 μM, P = 0.050), ALP activity (20 μM, P = 0.008) and calcium nodule formation (20 μM, P = 0.011) in a dose-dependent manner. Puerarin (20 μM) promoted osteocalcin secretion (P = 0.004) and the protein expression of both osteopontin (P = 0.001) and osteoprotegerin (P = 0.003). As to adipogenesis, puerarin suppressed adipocytes formation and intracellular triglyceride level (P = 0.001). In addition, puerarin (20 μM) decreased the mRNA and protein levels of CCAAT/enhancer binding protein α (P = 0.001, P = 0.002), proliferator-activated receptor γ (P = 0.005, P = 0.003), and adipocyte lipid-binding protein 4 (P = 0.001, P = 0.001). Moreover, phosphorylation of AKT1-Ser(437) (10 μM, P = 0.003; 20 μM, P = 0.007) and GSK-Ser(9) (10 μM, P = 0.005; 20 μM, P = 0.003), and the nuclear translocation of β-catenin (10 μM, P = 0.006; 10 μM, P = 0.002) were increased in 3T3-L1 cells treated by puerarin. CONCLUSION: Puerarin promoted osteogenesis and inhibited adipogenesis in vivo, and Akt/GSK-3β/β-catenin signaling pathway was involved in the suppression of adipogenesis.