Objective To observe the expression variation of serum tartrate-resistant acid phosphatase isoform 5b (TRACP-5b) in rats exposed to coal-burning fluorine, and explore the role of bone resorption in the pathogenesis of skeletal fluorosis.
Methods One hundred and twenty SD rats weaned for 4 weeks were divided into 4 groups: 1 control group was fed with commercial feed, and the other 3 experimental groups were fed with mixed feeds which contained 9.56 mg/kg (low-dose group), 15.89 mg/kg (mediumdose group), and 23.00 mg/kg (high-dose group) of fluorine. The animals were executed after 30 d, 90 d, and 180 d of treatment to determine bone and urinary fluoride content, incidence rate of dental fluorosis, and femur pathological score. TRACP-5b levels in serum were tested by ELISA.
Results (1) The bone and urinary fluoride concentrations, the dental fluorosis incidences, and the femur pathological scores of the 3 experimental groups were significantly increased in a dose-dependent manner respectively (all P< 0.05). After the treatment for 30 d, 60 d, and 90 d, the urinary and bone fluoride concentrations of each experimental group were statistically higher than the control group (all P< 0.05), and those of the higher dose group were remarkably higher than those of the lower dose group respectively (all P< 0.05). For 90 d and 180 d, the incidence of dental fluorosis in each dose group was obviously higher than that of controls (all P< 0.05); the femur pathological score of the medium-dose and the high-dose groups were significantly higher than that of the low-dose group and the controls (all P< 0.05). (2) The serum TRACP-5b levels in each experimental group with 180 d of exposure were statistically higher than those in the same dose group with 30 d and 90 d of exposure (all P< 0.05). There was no significant difference in the serum TRACP-5b among the groups after treatment for 30 d and 90 d. After the treatment for 180 d, the TRACP-5b levels of the high-dose group was significantly higher than that of the controls (all P< 0.05), and no significantly differences were found among the other groups.
Conclusion Exposure to high doses of fluorine for a longterm basis may cause elevated expression of serum TRACP-5b.
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