Empirical study of iodine on inducing NOD and Balb/c mice thyroiditis / 中国地方病学杂志

ABSTRACT

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 NaI 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 Nal 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 Nal 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 Balb/c mice showed a decreasing tendency(t values 1.374,1.567, all P > 0.05). TSH of Nal group showed an increasing tendency in Balb/c 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±056)μg/L, t values-3.562, P< 0.01], but no change of TgAb and TPOAb level in Nal group(1281,1364 cpm, 2.50×103, 0.14×103U/L were observed, compared with control(1297,1220 cpm, 3.17×103,0.03×103 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 lymphoeytes, 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/c mice. Besides, NOD mice have generate inflammatory reaction in thyroid and produced sensitized lymphocytes to Tg. Iodine excess can induce NOD mice to occur autoimmune thyroiditis.