碘对小鼠产后甲状腺炎影响的实验研究

目的 探讨碘对小鼠产后甲状腺炎(postpartum thyroiditis,PPT)发生,发展的影响.方法 44只8周龄雌性C57BL/6J小鼠均饲以低碘饲料(含碘量≤35 μg/kg),按体质量随机分成4组:非妊娠实验性自身免疫性甲状腺炎(EAT)组 8只,采用猪甲状腺球蛋白加完全弗氏佐剂复制EAT模型,最终存活6只,NI-PPT组(正常碘),10HI-PPT组(10倍碘),50HI-PPT组(50倍碘)各12只,复制EAT模型(方法 同非妊娠EAT组)后,与性成熟雄鼠交配,分别有7,6,6只小鼠受孕.4 组鼠分别饮用含KI为0.3,0.3,3.0,15.0 mg/L的碘水.妊娠母鼠生产4周后,观察4组小鼠甲状腺组织病理改变,血清中甲状腺球蛋白抗体(Tg-Ab)和甲状腺过氧化物酶抗体(TPO-Ab)水平,血清中甲状腺激素(TT3,TT4)水平以及脾脏中IFN-γ,和IL-4 mRNA的表达水平.结果 甲状腺组织病理检查示甲状腺内炎细胞浸润,上皮细胞扁平,滤泡萎缩或破坏.非妊娠EAT组,NI-PPT组,10HI-PVT组小鼠的炎细胞浸润程度均低于50HI-PPT组,组间两两比较,差异有统计学意义(P＜0.05).非妊娠EAT组,NI-PPT组,10HI-PPT组和50HI-PPT组的血清TPO-Ab水平分别为(14.32±8.85)%,(64.45±10.52)%,(38.46±5.57)%,(90.09±9.98)%,任意两组组间比较,差异均有统计学意义(P＜0.05),血清Tg-Ab水平分别为(33.74±3.71)%,(29.65±2.06)%,(37.21±3.87)%,(33.87±4.17)%,组间比较差异无统计学意义(F＝0.484,P＞0.05),血清TT3水平分别为(2.47±0.69)%,(1.57±0.25)%,(1.60±0.28)%,(1.82±0.75)%,组间比较差异无统计学意义(F＝1.596,P＞0.05),非妊娠EAT组,NI-PPT组和10HI-PPT组血清中TT4水平(99.87±5.97)%,(89.13±7.64)%,(91.05±5.82)%]与50HI-PPT组(66.68±5.47)%]比较,差异均有统计学意义(P＜0.05).在非妊娠EAT组,NI-PPT组,10HI-PPT组和50HI-PPT组,小鼠脾脏IFN-γmRNA表达水平分别为1.02±0.10,1.37±0.10,1.39±0.12,1.68±0.06,除NI-PPT组和10HI-PVF组的组间比较之外,其他的任意两组组间比较.差异均有统计学意义(P＜0.05),IL-4 mRNA表达水平分别为0.24±0.05,0.35±0.05,0.49±0.04,0.53±0.06.10HI-PPT组,50HI-PPT组与非妊娠EAT组和NI-PPT组比较,差异均有统计学意义(P＜0.05).结论 妊娠及产后易诱发PPT,增加适量碘的摄入量,可降低PPT的炎症反应,而补碘过量也是诱发或增加产后甲状腺炎发生的重要因素.因此,妊娠及产后补碘应遵循合理和科学的原则.

Effect of iodine on the pathogenesis of postpartum thyroiditis

Objective To explore the effect of iodine on the pathogenesis of postpartum thymiditis.Methods Forty-four female C57BL/6J mice,8-week old,fed by low iodine dietary(the concentration of iodine≤35 μg/kg),were randomly divided into 4 groups:non-pregnancy experimental autoimmune thymiditis(non-pregnancy EAT)group with 8 mice,EAT of mice was induced by immunization with pig's thyroglobulin(Tg)in the presence of complete Freund's adjuvant.Six mice in non-pregnancy EAT group survived at the end of experiment;normal iodine-PPT(NI-PPT)group,10-fold high iodine-PPT(10HI-PPT)group and 50-fold high iodine-PPT(50HI-PPT)group with 12 mice in each group.The last 3 groups mice,who received the same immunization schedule as the above,were mated with adult male mice followed by induction of EAT.In the end,7,6 and 6 mice were noticed to be pregnant in each group.All animals were killed 4 weeks after postpartum.Histological severity of thyroid specimens was evaluated.The serum level of thyroglobulin antibody(Tg-Ab),thyroid pomxidase antibody(TPO-Ab),TT3 and TT4 were measured by radioimmunoassay(RIA).The expression level of IFN-γ/IL-4 mRNA in spleenwere assayed by RT-PCR.Results Pathological examination showed the infiltration of inflammatory cells.epithelial cell applanation,follicle atrophy or destruction.The severity of inflammation in non-pregnancy EAT bgroup.NI-PPT group and 10HI-PPT group was less serious than that in the 50HI-PPT group,the difference has bstatistical significance(P＜0.05).The level of TPO-Ab in non-pregnancy EAT group,NI-PPI-group,10HI-PPTgroup and 50HI-PPT group wag(14.32±8.85)%,(64.45±10.52)%,(38.46±5.57)%and(90.09±9.98)%.respectively the difference being statistically significant between any two groups(P＜0.05).There was no statisticaldifference(F＝0.484,P＞0.05)of Tg-Ab among non-pregnancy EAT group(33.74±3.71)%],NI-PPT group (29.65±2.06)%],10HI-PPT group(37.21±3.87)%]and 50HI-PPT group(33.87±4.17)%].There was no statistical difference(F＝1.596,P＞0.05)of TT3 among non-pregnancy EAT group (2.47±0.69)%,NI-PPT group(1.57±0.25)%,10HI-PPT group(1.60±0.28)%]and 50HI-PPT group(1.82±0.75)%].The level of TT4 in 50HI-PPT group(66.68±5.47)%]was lower than that in non-pregnancy group,NI-PPT group and 10HI-PPTgroup(99.87±5.97)%,(89.13±7.64)%and(91.05±5.82)%],the difference being statistically significant(P＜0.05).The expression level of IFN-γ mRNA was increasing,being 1.02±0.10,1.37±0.10,1.39±0.12 and 1.68±0.06 in non-pregnancy EAT group,NI-PPT group,10HI-PPT group and 50HI-PPT group.The difference had a statistical significance between any two groups except for NI-PPT group and 10HI-PPT group(P＜0.05).The expression level of IL-4 mRNA in 10HI-PPT group(0.49±0.04)and 50HI-PPT group(0.53±0.06)were all higher than non-pregnancy EAT group(0.24±0.05)and NI-PPT group(0.35±O.05),the differences being statistically significant (P＜0.05).Conclusions Adequate iodine supplementation during pregnancy and postpartum period is necessary,but iodine excess could induce postpartum thyroiditis.So iodine supplementation during pregnancy and postpartum should be adequate and reasonable.