ABSTRACT
Objective To study the influence of fluoride on the expression of osteoprotegerin(OPG) mRNA and protein in suckling rat osteoblasts. Methods Osteoblasts obtained from calvarial of suckling Wistar rats were cultured in vitro in the media supplemented with NaF at a series of doses[O(control), 1,2 and 4 mg/L groups], and OPG mRNA expression and protein were evaluated by RT-PCR and ELISA methods, respectively. Results OPG mRNA expression in suckling rat osteoblasts cultured in vitro significantly increased after exposure to NaF for 48 h and 72 h(F=333.48,808.34,P<0.05). OPG mRNA expression in suckling rat osteoblasts cultured in vitro after exposure to NaF for 48 h at different doses(0.810±0.003, 0.819±0.031 and 0.870±0.044 for 1,2 and 4 mg/L groups, respectively) compared with that of control (0.800±0.040, all P<0.05). OPG mRNA expression further increased for 72 h exposure to NaF(0.933±0.047,1.031±0.051,1.240±0.062 for 1,2 and 4 mg/L, respectively), significantly higher than that of the control (0.805±0.020,all P<0.05) and corresponding groups at 48 h. NaF doses and time exposure exhibited a significant synergistic effect on OPG mRNA expression(F=2004.16, P<0.05). NaF also enhanced OPG protein expression in suckling rat osteoblasts cultured in vitro. Significant differences were observed only in 4 mg/L group(0.228±0.014,0.277±0.048) and control(0.205±0.012,0.229±0.010) at 48 h and 72 h (P<0.05). In addition, OPG protein expression at 72 h post-exposure was higher than that at 48 h,but there was no synergistic effect between concentration and time(F=1.21,P>0.05). Conclusions The results suggested that NaF could increase OPG mRNA and protein expression in suckling rat osteoblasts with a synergistic effect between the doses and exposure time.