2006 - Effects of High F-/High I on thyroid - rats

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69. 国秀娟,单忠艳, 滕卫平,氟过量与碘氟过量对甲状腺功能和形态影响的实验研究, 中华内科杂志, 2006 45(10):846-847
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Xiu et al. - "Experimental study on the effects of excessive fluoride and iodine on thyroid function and morphology" Chinese Journal of Internal Medicine 45(10):846-847 (2006)

氟过量对甲状腺的影响一直有争议.本课题组进行甲状腺疾病的流行病学调查时发现有高碘高氟地区,本研究模拟流行病学调查地区相应的氟、碘浓度,通过观察正常与高碘条件下氟过量对大鼠甲状腺功能、形态的影响,以确定氟过量与碘过量能否发挥协同作用.
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【Abstract】 Iodine and fluorine are two kinds of essential trace elements for human being. The intake of them is more dependent on the environment surrounded. Our government has established the law of universal salt iodated ( USI) from 1996. In order to acknowledge the situation of thyroid disease in population, we have taken an cross - section study in three different iodine intake regions. The results show the increasing incidence of hypothyroidism and thyroid carcinoma. Due to the u-biquitous nature of exposures to high iodine and fluorine in China and the issue of whether fluorine affected thyroid is still controversial, we hope to investigate the action of excess fluorine on thyroid. According to the concentrations of fluorine and iodine in the studied area, the animal experiment was designed to evaluate the effects of single and combined excess of fluorine and iodine on the thyroid gland function and structure in rats to investigate the mechanism to explore complex relationship between the trace elements and to afford the theory for therapy."iMaterials and Methods1. animals and the treatmentOne hundred and sixty Wistar rats of both sexes, 5 weeks old (125 -165g body weight) provided and treated by the laboratory animal department of China Medical University, were divided randomly into 8 groups and were individually housed and fed normal diets. Rats of three groups had free access to deionized drinking water with three different concentrations of fluorine respectively ( 15ppmF, 30ppmF, 60ppmF). One excess iodine group ( 1200ug/L I) , and other threegroups were given respectively three different excess fluorine added the equivalent concentration of excess iodine as above - mentioned. Two groups were given the deionized water without fluorine and iodine as controls.Rats were anaesthetized with ether half - and -.half after feeding for 75 days and 150 days. Blood collected by cardiac puncture before the rats were killed, was transferred to a test tube with no anticoagulant to obtain serum by centrifugation, then was immediately frozen at - 70℃ until analysis. The thyroid gland removed immediately after the death of rats was measured the weight and was stored under two different conditions as follows: (1) fixed in 4% PFA (0. 1M PBS, pH7.4 at 4℃ ) for light microscopy studies. (2) fixed in 2.5% glut-araldehyde (pH7.3 at 4℃ ) for electron microscopy studies.2. Assay methodsSerum T3 and T4 concentrations were determined by the RIA method and TSH concentration by the IRMA method. All kits were purchased from DPC (USA). Urinary iodine was measured according to the Ce/As method and urinary fluorine by fluorine ion selective e-lectrode.3. Thyroid Morphology and morphological examination Thyroid lobe from each rat was embedded in paraffin. Sections(3um) were stained with hematoxylin and eosin. We measured the area of colloid lumens, the heights of epithelial cells and the heights of cell nucleus using Metamorph/DP10/BX51.4. Transmission electron microscopyThyroid tissue were prepared for electron microscopy using standard procedures and the ultrathin sections were examined and photographed by a JEOL 1200 EX electron microscope.5. Statistical AnalysisData were analyzed using SPSS 10. 0 for Windows software. The results were expressed as the mean ± SD. Comparisons between groups were performed by one - way ANOVA, followed by the SNK test, to detect significance of difference among multiple groups p <0.05 indicated a statistically significant difference.Results1. Urinary iodineAt two time points, the levels of urinary iodine in the excess iodine group and all excess, iodine - fluorine groups were significantly higher than in the control group.2. Urinary fluorineAt the 75th day, the levels of urinary fluorine in excess fluorine III group and excess iodine - fluorine III group were significantly higher than in the control group, and the levels at the 150th day were significantly higher than in the control group or their levels at the 75th day.3. Serum TT3, TT4and 还原