低碘后补充不同碘水平饮食对大鼠肿瘤坏死因子和干扰素mRNA表达的影响

Effect of supplying iodine after iodine deficiency on the expression of splenic TNF-αand IFN-γmRNA

目的大鼠低碘后,补充不同碘水平饮食,观察其甲状腺组织形态、甲状腺激素水平和脾脏中肿瘤坏死因子(TNF-α)和干扰素(IFN-γ)的mRNA表达,探讨低碘后补碘对大鼠的影响。方法选用Wistar大鼠,低碘饲料加去离子水饲养3个月为低碘组(LI组),低碘后补充适碘饮食为LI-1×KI组,补充高碘饮食为LI-50×KI组,均补碘3个月,另设适碘对照组(NI组)。检测4组大鼠血清中甲状腺激素水平、甲状腺组织形态、脾脏中TNF-α和IFN-γmRNA的表达。结果LI组大鼠血清中T3和T4水平下降,甲状腺滤泡内胶质稀少,甲状腺上皮细胞呈增生、肥大等典型的低碘表现,脾脏中TNF-α和IFN-γ的mRNA表达也明显低于NI组。低碘后补充适碘饮食的LI-1×KI组,不仅使血清中T3和T4水平和甲状腺上皮细胞的形态逐渐恢复正常,TNF-α和IFN-γ的mRNA表达也明显提高。而低碘后补充高碘饮食的LI-50×KI组,甲状腺激素水平和TNF-α和IFN-γ的mRNA表达也均明显上升,但甲状腺组织形态虽有所好转,与LI-1×KI组比较尚有明显差异,且甲状腺滤泡有胶质潴留。结论低碘后补充适当水平的碘,其甲状腺激素水平、TNF-α和IFN-γ的mRNA表达及甲状腺组织形态的改变可逐渐恢复正常,呈可逆性。而低碘后补充高碘饮食,其甲状腺组织形态学的改变尚难恢复为正常。

Objective To study the changes of thyroid morphology,thyroxine(T4),triiodothyronine(T3) and the expression of splenic TNF-αand IFN-γmRNA during supplying iodine after iodine deficiency.Methods Wistar rats were fed with iodine deficiency fodder and free-ion water for three months as low iodine group(LI).Then some mice from LI were supplied with normal iodine for threes months as LI-1×KI group and supplied with high iodine diet for three months as LI-50×KI group.We also assigned a normal control group for assessing the differences of thyroid morphology,T3,T4 and the expression of splenic TNF-αand IFN-γmRNA among the four groups.Results After three months' iodine deficiency,serum thyroid hormone level significantly decreased and thyroid epitheliocytes were hyperplasia and hypertrophy as well as colloid was scarce in thyroid follicles in Wistar rats.At the same time the expression of splenic TNF-αand IFN-γmRNA was significantly lower compared with the control group.When supplied with normal iodine,T3,T4 and thyroid epithelium structure returned to normal.Additionally,the expression of splenic IFN-αand IFN-γmRNA was significantly increased.When supplied with high iodine,T3,T4 and the expression of splenic TNF-αand IFN-γmRNA approached to normal,but compared with those supplied with normal iodine,thyroid morphology was still significantly different with colloid retention in thyroid follicles though partly recovered.Conclusions The changes of thyroid hormone,thyroid structure and the expression of splenic TNF-αand IFN-γmRNA in mice after iodine deficiency were reversible when supplied with nomal iodine.While supplied with high iodine,thyroid structure couldn't recover as normal.