The effect of fluoride on osteoclast in bone tissue of rats and its mechanism / 中华地方病学杂志

ABSTRACT

Objective To investigate the effect of fluoride on osteoclast in bone tissue of rats and its mechanism.Methods Twenty specific pathogen free male Wistar rats aged 3 weeks were randomly divided into two groups by weight (each group has 10).The rats of control group drink distilled water and treatment group drink distilled water containing 100 mg/L fluoride.The rats were fed for 3 month.The dental fluorosis in rats was observed.The ion selective electrode method was used to measure bone fluoride accumulation.The pathological changes of bone tissue in rats were observed under light microscope.The osteoclast was identified by tartrateresistant acid phosphatase (TRAP) staining.The calcineurin (CaN) activity of serum was measured by detection of free phosphate with malachite green.The bicinchoninic acid (BCA) method was used to detect total protein concentration of serum.The colorimetry method was used to detect calcium and malondialdehyde (MDA) levels in serum.The enzyme linked immunosorbent assay (ELISA) method was used to detect calmodulin (CaM) content.Results By the end of the experiment,none dental fluorosis was detected in control group,all rats in fluoride group had dental fluorosis.The bone fluoride content of rats in fluoride group [(4 460.671 ± 418.548) mg/kg] was about 7.6 times higher than that in control group [(582.534 ± 58.342) mg/kg,t =-29.020,P ＜ 0.01].Compared with the control group,the bone tissue of rats in fluoride group showed thicker bone trabecular,sclerotin fusion and incomplete mineralization.Positive signal intensity of TRAP staining of bone tissue in fluoride group was significantly higher than that in control group.The number of osteoclast formation in fluoride group [10 (5-12)] was significantly higher than that in control group [3 (2-4);U =92.5,P ＜ 0.01].CaN activity in serum of rats in fluoride group [(3.334 ± 0.654) nmol/mg prot] was significantly higher than that in control group [(1.289 ± 0.361) nmol/mg prot;t =-6.346,P ＜ 0.01].The Ca and CaM content of serum in rats were not significantly different between the two groups.However MDA content in fluoride group [(7.703 ± 2.954) μmol/L] was significantly higher than that in control group [(3.958 ± 1.965) μmol/L,t =-2.968,P ＜ 0.05].Conclusion Excessive fluoride may increase osteoclast formation in bone tissue of rats,and the mechanism might be fluoride stimulated CaN activity through oxidative stress pathway.