| ObjectiveChina has been regarded as one of the countries suffering seriously from the prevalence of endemic flurosis which becomes a regional disease widely spreading around the world.The research concerning the influence of the combination of selenium and vitamin C on endemic fluorosis has not yet been reported. Based on the individual effect of selenium and vitamin C, this paper provided reference for the subsequent researches of the combination of selenium and vitamin C against endemic fluorosis, by means of investigating the effects of selenium and vitamin C in different dosages on oxidative stress, DNA damage and Bcl-2 protein expression induced by large amounts of fluoride.MethodsHealthy rats were randomly arranged into the negative control group, the group with high concentration of fluoride, the group with low concentration of selenium, the group with medium concentration of selenium, the group with high concentration of selenium, the group with low concentration of vitamin C, the group with medium concentration of vitamin C, the group with high concentration of vitamin C.Except for the rats in the negative control group drinking water and lavaged by distilled water, rats in the other groups drank sodium fluoride of 150mg/ml and lavaged by corresponding amounts of sodium selenite (4ug/ml of sodium selenite for the rats in the group with low concentration of selenium; 8ug/ml of sodium selenite for the rats in the group with medium concentration of selenium; 16ug/ml of sodium selenite for the rats in the group with high concentration of selenium) or solution of vitamin C (0.01g/ml of solution of vitamin C for the rats in the group with low concentration of vitamin C;0.02g/ml of solution of vitamin C for the rats in the group with medium concentration of vitamin C;0.04g/ml of solution of vitamin C for the rats in the group with high concentration of vitamin C). The average of volume of administration belonged to 5ml/kg of weight and the administration time totaled one month, averaging one time per day. After the administration of drugs for one month, rats were sacrificed and the leaving samples collected were dealt with as below:1.The concentration of fluoride ions existing in the urine of rats was measured by the analysis with ion selective electrodes and the coefficients of their livers and kidneys were measured as well.2.The measurement of corresponding indexes of oxidative stress of livers and kidneys of rats in each group: The concentration of malonaldehyde (MDA) was measured by the method of thiobarbituric acid (TBA) color development; The activity of glutathione peroxidase (GSH-Px) was measured by the method of dithiobinitrobenzoic acid (DTNB); The activity of superoxide dismutase (SOD) was measured by the method of pyrogallol auto-oxidation.3.The ratio of DNA damage of liver and kidney of rats in each group was measured by the method of single cell gel electrophoresis.4.The level of Bcl-2 protein expression of liver and kidney tissues was observed by the method of Envision TM.Results1.The results of the concentration of fluoride ions from urines as well as the organ coefficients tested indicated: The concentration of fluoride ions from urines of rats in each group drinking the solution of sodium fluoride was all increased, in which the differences between the negative control groups and the group with high concentration of fluoride possessed statistical significance (P<0.05), suggesting the excretion of fluoride ions existing in urines stimulated by the drinking of the solution of sodium fluoride. The differences of the group with medium concentration of selenium, the group with low concentration of vitamin C and the group with medium concentration of vitamin C respectively with the negative control group exhibited statistical significance while the differences of those with positive control groups showed no statistical significance, indicating that the selenium in high concentration as well as the vitamin C in low and medium concentration could not change the increasing amounts of fluoride ions in urines resulting from the drinking of the solution of sodium fluoride. There existed statistical significance between the group with low concentration of selenium and the group with high concentration of fluoride (P<0.05), whereas no statistical significance was shown between the group with low concentration of selenium and the negative control group. The differences of organ coefficients in each group exhibited no statistical significance.2.The measuring results of the corresponding indexes of oxidative stress from liver and kidney tissues revealed that, in comparison with activity of the GSH-Px of liver tissues from the rats in the negative control group as well as the group with high concentration of fluoride, that from the rats of groups with each level of selenium and vitamin C were all increased, suggesting the existence of statistical significance (P<0.05). There existed no statistical significance among the differences of the concentration of MDA of liver tissues from rats in each group. Compared with the activity of SOD of liver tissues from the rats in the negative control group as well as the group with high concentration of fluoride, that from the rats in the group with low concentration of selenium was evidently increased, indicating the differences possessed statistical significance(P<0.05). There existed a significant increase of the activity of GSH-Px in the group with high concentration of fluoride, compared with that in the negative control group, suggesting the existence of statistical significance (P<0.05). In addition, the differences of the activity of GSH-Px between the group with low concentration of vitamin C and the group with high concentration of fluoride possessed statistical significance (P<0.05). The differences of the concentration of MDA between the groups with low concentration of selenium and medium concentration of selenium respectively exhibited statistical significance and the differences of the concentration of MDA between the group with high concentration of selenium and the group with low concentration of vitamin C respectively and the group with high concentration of fluoride possessed statistical significance as well.3.The measuring results of DNA damage indicated that, the ratio of DNA damage of liver tissues in the group with high concentration of fluoride,in comparation with that in the negative control group,was increased and possessed statistical significance. There existed statistical significance in the differences of DNA damage of liver tissues between the group with low concentration of selenium as well as the group with high concentration of selenium respectively with the group with high concentration of fluoride being. In addition, the difference of DNA damage of liver tissues between the group with medium concentration of selenium being and negative control group possessed statistical significance while that between the group with medium concentration of selenium and the group with high concentration of fluoride exhibited no statistical significance. There existed no statistical significance of DNA damage of liver tissues between the group with high concentration of vitamin C as well as the group with medium concentration of vitamin C and the group with high concentration of fluoride (P>0.05). No statistical significance of DNA damage of kidney tissues was shown between the negative control group and the group with high concentration of fluoride (P>0.05). The differences of DNA damage of kidney tissues between the groups with each amount of selenium and the group with high concentration of fluoride possessed no statistical significance (P>0.05) as well. Nevertheless, there existed statistical significance of the differences of DNA damage of kidney tissues between the groups with each amount of vitamin C and the group with high concentration of fluoride (P<0.05).4.The measuring results of Bcl-2 protein expression revealed that the Bcl-2 protein expression of liver and kidney tissues among each group was not transparent and the differences of average optical density values were of no statistical significance (P>0.05). Compared with those of the negative control group, the average optical density values of the group with high concentration of fluoride decreased a little but their differences possessed no statistical significance (P>0.05). The average optical density values of liver tissues gradually increased as the increment of the amounts of selenium and vitamin C, whereas showing no statistical significance of the result.Conclusions1.After the administration of drugs, the concentration of fluoride irons from urines was remarkably increased, suggesting that the fluoride experiment was successful. Low dose of selenium can improved the increase, and had the protection function to fluoride-induced kidney damage.2.After the administration of drugs,the lipid peroxidation of rats liver was not evident, indicating that the liver had compensation to the fluoride-induced lipid peroxidation.3.After the administration of drugs,the DNA of liver was observably damaged. low and medium concentrations of selenium had antagonism to DNA damage of liver. All concentration of vitamin C in this experiment had kidney poison when combined with sodium fluoride. The mechanism is subject to further investigation, speculating that was related to experiment doses and experiment period.4.After the administration of drugs,though the Bcl-2 protein expression of liver and kidney was decreased, there were no remarkably statistical significance, demonstrating that, in these experiment conditions, sodium fluoride had not restrained the Bcl-2 protein expression of liver and kidney.
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