摘要
目的探讨慢性轻中度碘过量对甲状腺细胞凋亡的影响，观察限碘后的恢复情况。方法将Wistar大鼠分人4组：对照组、1．5倍、3倍和6倍高碘组，每日给碘量分别为4、6、12和24μg，于实验1至8个月分批处死动物。部分高碘8个月大鼠限碘3个月（4μg/d）。采用砷铈催化分光光度法测定尿碘浓度，应用AnnexinV染色流式细胞术和电镜对甲状腺细胞凋亡定量定性，碘化丙碇染色流式细胞术测定细胞周期，分子探针（DCFH-DA）荧光定量细胞内活性氧簇（ROS）水平。应用流式细胞术和免疫组织化学方法检测凋亡相关蛋白的表达。结果3倍和6倍高碘组4个月和8个月时，甲状腺细胞凋亡率和ROS水平显著高于对照（均P〈0．05），限碘后恢复正常。6倍碘组4个月和8个月时，甲状腺增殖期细胞比例著升高（5％和6％螂3％，均P〈0．05），静止期细胞比例显著下降（64％和67％铘80％，均P〈0．05）。3倍和6倍碘组8个月时，Fas、FasL、TRAIL蛋白表达水平比对照组高2～4倍，限碘后未恢复。Bcl-2和Bax蛋白的表达不变。6倍碘组8个月时，细胞凋亡率、ROS水平及给碘量三者之间显著正相关（r=0．637～0．790，P〈0．01）。结论慢性碘过量能增加甲状腺细胞凋亡，ROS过多产生可能涉及其机制。
Objective To explore the chronic effects of mild and moderate iodine excess and iodine restriction on apoptosis of thyrocytes. Methods Wistar rats were exposed to 4 different doses of iodine ： 4 μg/d （control）, 6 μg/d （1.5 fold iodine excess）, 12 μg/d （3 fold iodine excess）, and 24 μg/d （6 fold iodine excess） for 1, 2, 4 and 8 months. Some rats treated for 8 months were fed with 4 μg/d iodine for another 3 months. Urinary iodine concentration was monitored by arsenic/cerium catalyzing spectrophotography. Apoptosis was determined by flow cytometry after Annexin V-FITC staining and uhrastructure assessment under electronic microscope. Cell cycle kinetics was analyzed by flow cytometry after propidium iodine staining. Fluorescent measurement by DCFH-DA probe was used to determine the intracellular reactive oxygen species （ROS） level. Expressions of apoptic proteins were analyzed by flow cytometry and immunohistochemistry. Results Apoptotosis rate and ROS production in thyrocytes were significantly increased in 3 and 6 fold iodine excess groups after 4 mouths and 8 mouths （ all P 〈 0. 05 ）, which was reversed with iodine restriction. 6 fold iodine exposure was proved to cause a reduction of cells in GOGl-phase （ 64% and 67% vs 80%, both P 〈 0.05 ） and a concomitant accumulation in S-phase （5% and 6% vs 3%, both P 〈0.05） after 4 months and 8 months. Expressions of Fas, FasL and TRAIL proteins in 3 and 6 fold iodine excess groups after 8 months were increased by 2 to 4 times compared with control group and did not return to normal after iodine restriction. Bcl-2 and Bax remained constant. Positive correlations were observed among iodine amount, apoptosis rate and ROS level in 6 fold iodine excess group after 8 months （r =0.637-0.790, P 〈 0. 01 ）. Conclusion Chronic iodine excess results in thyrocyte apoptosis due probably to generation of ROS.
出处
《中华内分泌代谢杂志》
CAS
CSCD
北大核心
2008年第6期649-653,共5页
Chinese Journal of Endocrinology and Metabolism
基金
基金项目：国家自然科学基金资助项目（30240013、30370680）
美国中华医学基金会资助项目（98-688）
辽宁省博士启动基金资助项目（20071043）
关键词
碘
甲状腺
细胞凋亡
自由基
Iodine
Thyroid gland
Apoptosis
Free radicals
