长期摄入过量碘大鼠甲状腺滤泡的体视学变化

The effect of iodine excess on thyroid stereology at rats

目的观察大鼠长期摄入过量碘时甲状腺的形态和体视学变化。方法选用W istar大鼠分别给予不同剂量的碘化钾,饲养6个月后处死观察甲状腺重量,组织学变化,甲状腺滤泡的体视学参数等指标。结果低碘组(LI)大鼠甲状腺明显肿大,呈小滤泡性增生,平均滤泡体积(V)和滤泡表面积(S)均明显低于适碘组(P<0.01),而滤泡表面积密度(Sv)、比表面积(S/V)、数密度(Nv)明显高于NI组(P<0.01)。各高碘组甲状腺未发生肿大,但组织学呈现多型性变化;5倍碘组、10倍碘组甲状腺滤泡体视学各项指标与NI组相比较均无明显差别;而50倍碘组滤泡的体积密度(Vv)、表面积密度(Sv)高于NI组;100倍碘组平均滤泡体积(V)和滤泡表面积(S)均低于NI组,而S/V、Nv则高于NI组;50倍碘组、100倍碘组的甲状腺呈现类似LI组的小滤泡增生,但增生的程度远低于LI组。结论长期摄入过量碘大鼠甲状腺虽然未出现甲状腺肿大,但组织学和体视学参数都发生了明显的变化,以50和100倍碘组的小滤泡增生更为明显。

Objectives To study the effect of iodine excess on thyroid stereology at rats. Methods Wistar rats were administrated potassium iodide of different concentration for six months. The following parameters were measured, ie, thyroid absolute and relative weight, histological morphology, and thyroid stereology. Results A visible thyroid enlargement with obvious follicular hyperplasia was found in LI group. Thyroid stereological parameters indicated that mean volume, mean surface and mean diameter of follicles in LI were significantly lower than those in NI, while surface density, specific surface and numerical density were remarkably higher. No goiter found in all iodine excess groups. Partial follicles in 5 HI and 10 HI became larger and partial follicles became small. There was no difference in all numerical parameters of thyroid follicles of 5 HI, 10 HI, and NI groups. Volume density and surface density in 50 HI were higher than those in NI. Mean volume, mean surface and mean diameter in 100 HI were lower compared with those in NI, and specific surface, numerical density was higher. Conclusions An excess of long term iodine intake results in definite histological and stereological changes in rat thyroid gland without goiter formation. Extremely high iodine intake, such as in 50 HI and 100 HI groups of our study, induces marked hyperplasia of follicle, indicating TSH stimulation existing in the thyroid gland.