Effects of hypoxia on gene expressions of osteoprotegerin and receptor activator of NF-κB ligand in mouse osteoblasts

Objective:To observe the effects of hypoxia on the gene expressions of osteoprotegerin(OPG) and receptor activator of NF-κB ligand(RANKL) in mouse osteoblasts.Methods:Primary mouse osteoblastic cells were obtained by the collagenase/trypsin enzyme digestion of excised calvarial bones from neonatal mice (born within 24 h), and cultured in vitro. After cultured for 3 to 5 serial subcultivation, the cells were randomly divided into hypoxic group(3% O_2) and normoxic group(20% O_2). Then the total cellular RNA was extracted at 6, 12, 24, 48 and 72 h from mouse osteoblasts and mRNA expressions of OPG and RANKL were examined using RT-PCR.Results:The mRNA expression of OPG in osteoblasts cultured in 3% O_2 at various times was significantly lower than that cultured in 20% O_2. The longer the cells were cultured in hypoxic condition, the lower the expression of OPG was. However, the mRNA expression of RANKL in osteoblasts cultured in 3% O_2 was significantly higher than that cultured in 20% O_2, especially at 24 h.Conclusion:The hypoxia can stimulate RANKL gene expression, but inhibit OPG gene expression in mouse osteoblasts in vitro.