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目的研究不同碘摄入水平对仔鼠大脑2型脱碘酶(D2)活力、髓鞘碱性蛋白(MBP)、突触蛋白Ⅰ表达的影响。方法将 SPA-VAF 级 Wistar 大鼠60只随机分为低碘组(LI 组)、正常碘组(NI 组)、5、10、50、100倍高碘组(HI 组),每组10只,雌、雄各半。经饮水给予碘酸钾,使其每日总碘摄入量分别为1、6.15、30.75、61.5、307.5、615μg。喂养3个月后雌、雄交配,仔鼠在出生后28 d 处死,以竞争结合放射免疫分析(RIA)法测定血清甲状腺激素(TH),以强阳离子交换层析法测定大脑 D2活力,以免疫组化方法检测 MBP 及突触蛋白Ⅰ表达的变化。结果与 NI 组比较,LI 组各血清 TH 水平均显著降低,差异有统计学意义(P<0.05,P<0.01);各 HI 组随着碘摄入量的增加各血清 TH 水平均呈降低趋势,其中 TT_4、FT_4在615μg/d 碘组降低,差异有统计学意义(P<0.05)。LI 组与各 HI 组的 D2活力较 NI 组有升高的趋势,但均无统计学意义(P>0.05)。与 NI 组比较,LI 组和各 HI 组胼胝体 MBP 蛋白表达均减少,海马 CA3区突触蛋白Ⅰ表达均增多。结论碘缺乏和重度碘过量(615μg/d 碘组)仔鼠表现出甲状腺功能减退,碘缺乏引起的甲状腺功能减退程度和对髓鞘与突触发育的影响比碘过量更为严重。
Objective To investigate the effects of different levels of iodine intake on the activity of type 2 deiodinase (D2), the expression of MBP and synapsin Ⅰ in offspring brain. Methods 60 Wistar rats with SPA-VAF were randomly divided into low iodine group (LI group), normal iodine group (NI group), 5, 10, 50, 100 and 100 times higher iodine group (HI group) Female, male half. Potassium iodate given by drinking water, so that the total daily intake of iodine were 1,6.15,30.75,61.5,307.5,615μg. Three months after feeding, female and male mice were mated. The offspring were sacrificed 28 days after birth. Serum thyroid hormone (TH) was determined by competitive radioimmunoassay (RIA) and the activity of D2 was determined by strong cation exchange chromatography Immunohistochemistry was used to detect the expression of MBP and synapse Ⅰ. Results Compared with NI group, the levels of TH in LI group were significantly decreased (P <0.05, P <0.01). The levels of serum TH decreased with the increase of iodine intake in each HI group , TT_4, FT_4 in the 615μg / d iodine group decreased, the difference was statistically significant (P <0.05). D2 activity in LI group and each HI group was higher than that in NI group, but there was no statistical significance (P> 0.05). Compared with NI group, the expression of MBP protein in corpus callosum in LI group and each HI group decreased, while the expression of synaptophysin Ⅰ in hippocampal CA3 area increased. Conclusions Iodine deficiency and severe iodine excess (615 μg / d iodine group) show thyroid hypothyroidism. The degree of hypothyroidism caused by iodine deficiency is more serious than the iodine excess in myelin sheath and synapse development.