中轻度过量补碘对非碘缺乏大鼠甲状腺功能和形态的影响

目的 研究中轻度过量补碘对非碘缺乏Wistar大鼠甲状腺功能和形态的影响。方法 将Wistas大鼠随机分为双蒸馏水(DDW)、3倍碘、6倍碘、10倍碘、20倍碘5组,每组10只。固相免疫放射分析法(IRMA)测大鼠血清促甲状腺激素(TSH),放射免疫分析法(RIA)测血清总T4(TT4)、总T3(TT3)、反T3(rT3)和甲状腺内TT4。砷铈分光光度法测定尿碘。光、电镜下观察,图像分析仪测量滤泡上皮细胞高度和滤泡腔面积。结果 与DDW组比较,补充3倍以上碘各组90d时血清TSH值增高,但差异无显著性;血清TT3明显降低(P=0．0001),TT4明显增高(P=0．001),组织TT4也明显增高(P=0．0001),血清rT3值无明显差异;滤泡腔面积增大,上皮细胞变扁,胞核染色深,滤泡融合破裂,巨滤泡形成,毛细血管减少;上皮细胞内质网扩张,次级溶酶体增多,微绒毛减少,染色体浓集。结论 补充3倍以上碘使非碘缺乏大鼠出现甲状腺功能减退倾向,抑制和破坏大部分甲状腺滤泡上皮细胞。

Effect of mild and moderate excessive iodine supplementation on thyroid function and morphology in non-iodine deficiency rat model

Objective To study the effect of moderate and mild iodine excess on thyroid function and morphology in non iodine deficiency Wistar rats Methods Serum thyroid stimulating hormone(TSH) was measured with solid phase radioimmunoassay(IRMA) and serum total T 4 (TT 4), TT 3, reverse T 3(rT 3) and thyroid TT 4 with radioimmunoassay (RIA) Cer Arsenite colormetric method was used to measure median urinary iodine (MUI) Thyroid morphological changes were observed under optical and electronic microscope Metamorphic imaging system was used to measure the height of thyrocytes and the areas of thyroid follicular cavities Results Iodine intake of three times than normal for 90 days could increase serum TSH but without significant difference; Serum TT 3 values were markedly lower than those in control, P = 0 000 1 Serum and thyroid TT 4 values were markedly higher than those in double distilled water (DDW) group, P value being 0 001 and 0 000 1 respectively However, serum rT 3 did not change markedly when compared with that in DDW group The area of follicular cavity increased, follicular cells became flat, nucleus stained darker, follicles broke and combined, giant follicles were formed, and the capillaries around the follicules were reduced The height of thyrocytes was markedly lower than those in DDW group, while the areas of thyroid follicular cavities were markedly larger than those in DDW group(both P values were 0 001) Thyroid ultrastructure showed enlargement of endoplasmic reticulum of thyroid follicular cells, increase of number of secondary lysosomes, darker stain of nuclei, condensation of chromatin and reduction of microvilli Conclusion Iodine intake over 3 times than normal may potentiate the possibility of hypothyroidism and inhibit the function of most of thyrocytes in non iodine deficiency rats