长期摄入过量碘大鼠甲状腺的形态学变化

Morphological study on thyroid gland of rats with an excess of long term iodine intake

目的观察大鼠长期摄入过量碘甲状腺的形态学变化。方法选用Wistar大鼠给予不同剂量的碘化钾,分别于实验3、6、12月时处死观察甲状腺质量、组织学变化、阳性增殖细胞数量等指标。结果低碘组大鼠甲状腺明显肿大,呈小滤泡性增生,阳性增殖细胞显著增多。各高碘组甲状腺虽未发生肿大,但发生了明显的组织学变化,主要表现为胶质蓄积,大滤泡增多,同时存在小滤泡增生;在5倍和10倍高碘(5HI,10HI)组两种变化均可见到,但在50倍和100倍高碘(50HI,100HI)组滤泡增生变得明显,阳性增殖细胞亦明显增多,但不及低碘组。结论长期摄入过量碘使大鼠甲状腺发生了明显组织学变化,但仍不足以形成甲状腺肿大;在50HI和100HI摄入时滤泡增生变得明显,提示甲状腺存在促甲状腺激素(TSH)刺激。

Objective To study the morphological alterations of the thyroid gland in rats subjected to a longterm iodine excess intake. Methods Wistar rats were fed on a diet with a different dosage of potassium iodide for3, 6 and 12 months. The thyroid glands were weighed, and routine tissue sections were prepared for H.E. andimmunohistochemistry staining for PCNA monoclonal antibody. Results A visible thyroid enlargement (goiter) withobvious follicular hyperplasia was found in low iodine group (LI), and the PCNA positive staining cells can be seenfrequently. No goiter occurred in all iodine excess groups, but some histological changes were found in thyroidtissues. The major changes included increased follicles with colloid accumulation and concurrence of follicularhyperplasia. These alterations can be found in 5-fold high iodine group(5HI) and 10-fold high iodine group(10HI),but in 50-fold high iodine group(50HI) and 100-fold high iodine group(100HI) the hyperplasia became remarkableand the PCNA positive cells were increased. Conclusions An excess of long term iodine intake results in definitehistological changes in rat thyroid gland without goiter formation. Extremely high iodine intake, such as in 50 HI and100 HI groups of our study, induces marked hyperplasia of follicle, indicating TSH stimulation existing in thethyroid gland.