摘要：
Objective To study the influence of excessive iodine intake on the 99Tcm-pertechnetate uptake function of thyroid and explore the related mechanism.Methods A total of 150 male Wistar rats were divided into normal iodine group (NI group) and 4 high iodine (HI) groups (10HI,50HI,100HI and 500HI group) with completely random method.Each group included 30 rats.Rats in HI groups were intragastrically administrated with different concentrations of KIO3,and rats in NI group were administrated with the same amount of distilled water.After a 7 d HI diet,each group was randomly divided into 3 subgroups:7 d group (HI diet for 7 d),10 d group (HI diet for 7 d + limiting iodine for 3 d) and 14 d group (HI diet for 7 d + limiting iodine for 7 d).All rats were given 1.85 MBq 99TcmO4-,then the thyroid glands were isolated and weighed 20 min post-injection.The radioactive counts were measured and the thyroid uptake percentage activity of injected dose per gram of tissue (％ID/g) of 99TcmO4-for each sample was calculated.Sodium-iodide symporter (NIS) expression level was analyzed by Western blot.One-way analysis of variance or Welch test was used to compare the differences among groups,and Spearman rank correlation analysis was also used.Results At the same observation time,the ％ID/g of 99TcmO4-and NIS expression among different HI groups were statistically significant (F values:48.825-119.219,all P＜0.01).In NI and 10 HI groups,％ID/g of 99TcmO4-and NIS expression were not significantly different among different time subgroups (F values:0.090-4.753,all P＞0.05).Significant differences of ％ ID/g of 99TcmO4-and NIS expression were found among different time subgroups in 50HI,100HI and 500HI groups (F values:10.442-90.408,all P＜0.01).Spearman correlation analysis showed that the concentration of iodine correlated negatively with ％ID/g of 99TcmO4-and NIS expression (rs values:-0.853 and-0.950,both P＜0.01),while the ％ID/g of 99TcmO4-and NIS expression was positively correlated (rs =0.925,P＜0.01).Conclusions Excessive iodine intake can inhibit thyroid uptake of 99TcmO4-in rats,which is associated with the down-regulation of NIS expression.The degree of inhibition correlates positively with iodine concentration,and correlates negatively with NIS expression.The degree of recovery of NIS and ％ID/g of 99TcmO4-may relate to the time of limiting the iodine intake.%目的 探讨碘过量摄人对大鼠甲状腺摄锝功能的影响及其机制.方法 按完全随机分组法将150只Wistar雄性大鼠分为对照组(NI组;30只)与多个高碘(HI)组(10HI、50HI、100HI、500HI组,每组30只).HI组采用不同浓度KIO3灌胃,NI组采用等量蒸馏水灌胃.处理7d后将各组再分为3个亚组[7d组(不同碘浓度干预7d)、10d组(不同碘浓度干预7d再限碘3d)和14 d组(不同碘浓度干预7d再限碘7d)].各组大鼠麻醉后经尾静脉注射99TcmO4-1.85 MBq,20 min后剥离大鼠甲状腺,称质量并测定放射性计数,计算大鼠甲状腺放射性摄锝率[每克组织百分注射剂量率(％ID/g)].采用Western blot法测定大鼠甲状腺组织中钠碘转运体(NIS)的表达水平.采用单因素方差分析或Welch检验比较组间差异,另行Spearman秩相关分析.结果 观察时间相同时,不同碘浓度组间摄锝率及NIS差异均有统计学意义(F值:48.825～ 119.219,均P＜0.01).不同碘浓度组中,NI组内和10HI组内各不同时间的摄锝率及NIS表达差异均无统计学意义(F值:0.090～4.753,均P＞0.05);50HI、100HI及500HI组内不同时间的摄锝率及NIS差异均有统计学意义(F值:10.442～90.408,均P＜0.01).碘浓度与摄锝率、NIS表达间呈负相关(rs值:-0.853和-0.950,均P＜0.01),摄锝率与NIS间呈正相关(rs=0.925,P＜0.01).结论 碘过量可通过下调NIS表达抑制大鼠甲状腺摄锝功能,其抑制程度与碘浓度呈正相关,与NIS表达呈负相关;限碘后甲状腺摄锝率及NIS恢复程度与限碘时间有关.
