| Objective:Observe rats fed with different concentrations of sodium selenite, molybdate, and sodium borate fluoride poisoning to find better trace elements against fluoride toxicity.Methods:This study includes two parts:Test I The effect of Selenium, Molybdenum, and Boron on fluoride metabolism in rats with chronic fluorosis.1. Select, group, and breed animals.64 Wistar rats were randomly divided into 8 groups: half male and half female. Each group were sub-cage artificially fed, using fluorine-containing water, which means quantitatively fed with Se Mo-B, and filled the rest with distilled water and normal diet. In addition to the negative control group (normal drinking water, diet), the experimental group (selenium, molybdenum, boron,and fluorine group) and dose group were drinking fluoride (F-)45mg/L of distilled water, the experimental group were fed with added selenium 0.3mg/kg, Selenium 1.5mg/kg, Mo 55mg/kg, Mo 82.2mg/kg, B 45mg/kg, B 55mg/kg. All groups are fed for 16 weeks.2. Methods(1) Weighed the weight of the rats at the beginning of the experiment and once every week. Recorded the weight and the general condition of rats.(2) Collected 24h urine samples every four weeks to detect the fluoride level and Hydroxyproline concentration in the urine.(3) Observed the rats of dental fluorosis, and classified the rats according to classification criteria of dental fluorosis rats to score dental fluorosis.(4) At the end of the 16th week, the rats were decapitated. The lower incisors of mandibular were fixed, decalcified, and sliced. TESTâ…¡:Observation of effects of Selenium, Molybdenum, and Boron on ameloblast morphology and the expression of PCNA, C-myc in fluorosis rat.(1) Observed the changes of ameloblasts morphological and organelles by light and electron microscopy.(2) Observed the occurrence of ameloblast apoptosis by TUNEL, and detected the expression of PCNA, C-myc, and CyclinD1 in ameloblast by immunohistochemistry. The semiquantitatively analyze of PCNA, C-myc, CyclinD1 were done by image analysis software.Results:1. As the experiment continues, the weight of each group gradually increases. The weight of selenium group is higher than that of the Mo group and B group. The difference is statistically significant (P<0.05). At the end of the 16th week, urine fluoride concentration of the fluoride group decreases, compared to the selenium group and molybdenum group. The difference is statistically significant (P<0.05).2. The dental fluorosis appears on every group in the fourth week. As the experiment continues, dental fluorosis appears moderately but not severely. At the end of the experiment, three fluorine-free cases occur in the selenium group. The difference is statistically significant (P<0.05). Mo group and B group have less severe dental fluorosis symptom compared to the fluoride group.3. At the end of the 16th week, the selenium group has lower urinary hydroxyproline than the fluoride group, the molybdenum group, and the B group. The result is statistically significant (p<0.05).4. For the HE staining result, the rat ameloblasts of the negative control group are oval, columnar and arranged in uniform. Fluoride group shows very irregular cell arrangement, as there appears a large number of cell distortion and thinning enamel. Selenium, molybdenum, and Boron group display conditions in between the two extreme.5. Electron microscopy results:all of the experimental groups have reduced organelles. Cell membrane, mitochondria, rough endoplasmic reticulum and nuclear membrane are damaged except negative control group. 6. Apoptosis, PCNA, C-myc expression.except the fluoride group, the experimental group causes the inhibition of cell apoptosis and C-myc expression, while promoting the expression of PCNA, selenium especially.Conclusion:1.Under the experimental conditions, selenium, molybdenum, and boron may have antagonistic effects on fluoride poisoning. As the results of the weight gaining in rats and formation of dental fluorosis suggest, selenium may play a more important role than molybdenum and boron.2. In this study, an increase in urinary hydroxyproline in the latter stage of fluorosis is consistent with previous findings.3. Light and electron microscopy results suggest that dental fluorosis may cause the damage of ameloblasts. Selenium, molybdenum, and boron have cell damage effect caused by antagonistic effects on fluorine.4.The mechanism of Selenium, molybdenum, and boron reducing fluoride toxicity may relate to the fluoride antagonistic effects that cause apoptosis of ameloblasts, enhancement of C-myc expression and inhibition of PCNA expression.
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