碘诱发NOD和Balb／c小鼠甲状腺炎的实验研究

Empirical study of iodine on inducing NOD and Balb/c mice thyroiditis

目的观察碘过量对不同遗传背景小鼠甲状腺炎诱发作用的异同。方法选用NOD和Balb／c小鼠各14只，每个品系小鼠均分为对照组、碘化钠（NaI）组，分别饮用纯净水和0．05％NaI水8周。放射免疫法（RIA）和ELISA法分别检测血清中总T4（TT4）、甲状腺球蛋白抗体（TgAb）、甲状腺过氧化物酶抗体（TPOAb）和促甲状腺激素（TSH）水平，光镜下观察甲状腺形态学改变和免疫组化染色的甲状腺细胞凋亡情况，四甲基偶氮唑兰（MTT）法检测颈部淋巴结和脾淋巴细胞对甲状腺球蛋白刺激的增殖反应。结果饮碘水8周后，NOD和Balb／c小鼠甲状腺相对质量，NaI组[（104．83±14．52）、（155．79±20．77）mg／kg]较对照组[（71．80±20．42）、（105．15±21．98）mg／kg]明显增加（t值分别为-3．293、-4．429，P均〈0．01），甲状腺组织表现为滤泡扩张、胶质潴留；NOD、Balb／c小鼠血清仉水平，NaI组[（29．52±4．42）、（19．53±2．35）nmol／L]较对照组[（33．40±5．38）、（23．47±6．22）nmol／L]呈下降趋势（t值分别为1．374、1．567，P〉0．05）；血清1、sH水平，与对照组[（3．55±1．41）、（5．55±0．56）μg／L]比较，Balb／c小鼠NaI组[（4．14±1．71）μg／L]呈升高趋势（t=-0．705，P〉0．05），NOD小鼠NaI组[（6．98±0．66）μg／L]明显升高（t=-3．562，P〈0．01）；NOD、Balb／c小鼠NaI组TgAb（1281、1364epm）和TPOAb水平（2．50×10^3、0．14×10^3U／L）与对照组（1297、1220cpm，3．17×10^3、0．03×10^3U／L）比较没有明显变化（Z值分别为-0．081、-0．703，-0．244、-1．293，P均〉0．05）。NOD小鼠NaI组甲状腺细胞凋亡数量较Balb／c小鼠增加，并且甲状腺内可见大量淋巴细胞浸润，组织结构破坏和纤维化的灶性病变；NOD小鼠淋巴结和脾淋巴细胞数量，NaI组（1．100±0．014、1．076±0．033）较对照组（0．993±0．011、1．0HD5±0．003）增加（t值分别为-11．672、-4．314，P均〈0．01）。结论碘可致Balb／c鼠甲状腺肿大，功能下降；NOD鼠除上述病变外，甲状腺发生明显炎症反应，并且针对Tg产生了致敏的淋巴细胞。碘过量可诱发NOD鼠发生自身免疫性甲状腺炎。

Objective To observe the different effects of iodine excess on inducing two strain mice thyroiditis. Methods NOD and Balb/c mice, each having 14 mice, were divided into NaI and control group. The mice were given 0.05% NaI water for 8 weeks in Nal group. RIA and ELISA were used respectively to detect TT4, TgAb, TPOAb and TSH level in serum. Morphology changes of thyroid and apoptosis of thyrocytes stained by immunohistochemistry were observed under light microscope. Lymphocytic proliferation of cervical lymph node and spleen to responding to Tg were detected by MTr method. Results After intake of iodine water for 8 weeks, NOD and Balb/c mice showed relative quality of thyroid in NaI group[ （104.83 ± 14.52）, （155.79 ± 20.77）mg/kg] obviously increased compared with control group[ （71.80 ± 20.42）, （105.15 ± 21.98）mg/kg, t values： - 3.293, - 4.429, all P〈 0.01）], enlarged follicular lumen with colloid accumulation were observed in thyroid. Serum level of TT4 in NaI group [ （29.52 ± 4.42 ）, （19.53 ± 2.35）nmol/L] to control group[33.40 ± 5.38）, （23.47 ± 6.22）nmol/L] of NOD and Batb/c mice showed a decreasing tendency（t values： 1.374,1.567, all P 〉 0.05）. TSH of NaI group showed an increasing tendency in Balb/e mice [ （4.14 ± 1.71 ） μg/L, compared with control [ （3.55 ± 1.41 ） μg/L, t values ： - 0.705, P 〉 0.05 ] and obviously increased in NOD mice [ （6.98 ± 0.66）μg/L, compared with control[（555 ±0.56）μg/L, t values： - 3.562, P 〈 0.01], but no change of TgAb and TPOAb level in NaI group（1281,1364 cpm, 2.50×10^3, 0.14×10^3U/L were observed, compared with control（1297,1220 cpm, 3.17 ×10^3,0.03 ×10^3 U/L; Zvalues： - 0.081, - 0.703, - 0.244, - 1.293, all P 〉 0.05）. In NOD mice NaI group, apoptosis of thyrocytes was more intense than Balb/c mice, obvious infiltration of lymphocytes, disorganization and focus fibrosis was seen in thyroid. The cell amount of NaI group increased in NOD mice lymph node and spleen cells [ （1.100 ± 0.014）, （1.076 ± 0.033 ） ] were more than that in the control group[ （0.993 ± 0.011 ）, （1.005 ± 0.003）, t value： - 11.672, - 4.314, P 〈 0.01 ）. Conclusions Iodine leads to enlargement of thyroid and malfunction of thyroid in Balb/e mice. Besides, NOD mice have generate inflammatory reaction in thyroid and produced sensitized lymphoeytes to Tg. Iodine excess can induce NOD mice to occur autoimmune thyroiditis.