ABSTRACT
Objective To study the influence of fluorine on signaling pathway of osteoprotegerin(OPG)/ receptor activator of NF-κB ligand(RANKL) in cultured rat osteoblasts.Methods Osteoblasts were isolated from skull of neonatal rats(＜ 24 hours) by enzyme digestion,and fluorine of different concentrations [0 (control),1 × 10-3,1 × 10-4,1 × 10-5,1 × l0-6 and 1 × 10-7 mol/L] were added into the culture medium of second generation of osteoblasts.The expressions of OPG and RANKL mRNA were determined using real-time PCR 24 and 48 hours after culturing.The expressions of OPG and RANKL protein were measured by Western blotting.Results ① After exposed to fluorine for 24 hours,the differences of RANKL and OPG mRNA expression had statistical significance between groups(F =30.95,22.62,all P ＜ 0.01),the expression of RANKL mRNA(5.99 ± 0.39) in the 1 × 10-5 mol/L group and the expressions of OPG mRNA(3.52 ± 0.09,4.81 ± 0.15,3.68 ± 0.04) in the 1 × 10-4,1 × 10-5 and 1 × 10-6 mol/L groups were higher than those of the control group(3.20 ± 0.19,3.09 ± 0.58,all P ＜ 0.05),but in the 1 × 10-3 mol/L group,RANKL mRNA(2.29 ± 0.18) was lower than that of the control group(P ＜ 0.05).After exposed to fluorine for 48 hours,the differences of RANKL and OPG mRNA expression had statistical significance between groups(F =26.62,5.72,all P ＜ 0.01),the expressions of RANKL and OPG mRNA(6.67 ± 0.49 and 5.05 ± 0.51) in the 1 × 10-5 mol/L group were higher than those of the control group(4.29 ± 0.07 and 4.34 ± 0.12,all P ＜ 0.05),and in the 1 × 10-3 mol/L group the expression of OPG mRNA(3.63 ± 0.49) was lower than that of the control group(P ＜ 0.05).② The expression of RANKL protein was not statistically significant between 24 hours and 48 hours groups (F =0.07,0.49,all P ＞ 0.05) ; the differences of OPG protein expression had statistical significance between groups(F =3.26,P ＜ 0.05),the expression of OPG protein in the 1 × 10-5 mol/L group(1.45 ± 0.10) was higher than that of the control group(1.05 ± 0.06,P ＜ 0.05) at the 24 hours.After 48 hours,the expression of OPG protein was not statistically significant(F =0.44,P ＞ 0.05).Conclusions At lower fluorine concentrations,bone formation is the main activity.But when fluorine concentration increased and time prolonged,the osteoclast differentiation and maturation are promoted,and the bone resorption is the main thing.