富碘中药海藻对甲状腺细胞凋亡及凋亡调控基因的影响

Effects of algae with iodine excess on thyroid cell apoptosis and apoptosis controlling gene

目的:通过观察富碘中药海藻对碘缺乏机体甲状腺滤泡上皮细胞凋亡,Fas,FasL,Bcl-2蛋白表达的影响,分析富碘中药过量对甲状腺损伤的机制。方法:实验于2006-03/09在辽宁中医药大学实验中心完成。①实验干预:选用健康鼠龄4周的Wistar大鼠150只。取120只喂低碘饲料建立缺碘大鼠模型,随机分为4组,每组30只:单纯高碘组喂含碘2000μg/L的双蒸水;模型组喂等体积双蒸水;常规剂量海藻组和3倍剂量海藻组分别灌胃海藻生药量13.5g/(kg·d)和40.5g/(kg·d)。以其余30只大鼠为正常对照组:正常饮食,每日灌服等体积双蒸水。②实验评估:分别在给药0,7,28d后取材。采用脱氧核糖核苷酸末端转移酶介导原位缺口末端标记确定甲状腺滤泡上皮细胞凋亡细胞数。采用免疫组化方法观察甲状腺滤泡上皮细胞Fas,FasL,bcl-2表达。结果:大鼠150只均进入结果分析。①凋亡细胞数:给药后7d,常规剂量海藻组和3倍剂量海藻组低于模型组,差异有非常显著性意义(P<0.01)。常规剂量海藻组和3倍剂量海藻组低于单纯高碘组,差异有显著性意义(P<0.05)。给药后28d,正常对照组甲状腺滤泡上皮细胞凋亡细胞数低于其他4组,差异有显著性或非常显著性意义(P<0.05～0.01)。常规剂量海藻组高于单纯高碘组,差异有显著性意义(P<0.05)。②Fas,FasL,Bcl-2蛋白表达:给药7d后,常规剂量海藻组和3倍剂量海藻组Fas蛋白的表达低于模型组,差异有显著性意义(P<0.05)。单纯高碘组和3倍剂量海藻组FasL表达低于模型组,差异有显著性意义(P<0.05)。常规剂量海藻组Bcl-2蛋白表达高于模型组,差异有显著性意义(P<0.05)。给药28d后,单纯高碘组和3倍剂量海藻组Fas蛋白的表达低于模型组,差异有显著性意义(P<0.05)。单纯高碘组、常规剂量海藻组和3倍剂量海藻组Bcl-2蛋白表达高于模型组,差异有显著性意义(P<0.05)。结论:富碘中药海藻给药28d可造成碘缺乏大鼠甲状腺细胞损伤,Fas,FasL,bcl-2可能参与诱导细胞凋亡。

AIM： To study the effects of algae with iodine excess on apoptosis and expressions of Fas, FasL and Bcl-2 in thyroid follicular epithelium induced by iodine deficiency. METHODS： The experiment was carded out in the Test Center of Uaoning University of Traditional Chinese Medicine from March to September in 2006. （1）A total of 150 4-week-old Wistar rats were used for this experiment, and 120 of them were fed with low-iodine fodders to induce iodine deficiency models, and were divided into 4 groups at random （n = 30）. Model group and pure higher iodine group were fed with double distilled water with 0 and 2 000 μg/L iodine load, respectively. The conventional dosage algae group and 3 times of dosage algae group were fed with algae 13.5 g/kg and 40.5 g/kg, respectively. The other 30 rats ware taken as normal control group, which were fed conventionally and administrated with the same volume of double distilled water.（2）Samples were obtained at days 0, 7, 28 of administration. Expressions of Fas, FasL and Bcl-2 were determined by immunohistochemistry. Transferase mediated dUTP nick and labeling was used to detect apoptosis of thyroid follicular epithelium. RESULTS： All of 150 rats were involved in the result analysis.（1）Apoptosis： Compared with model group, the conventional dosage algae group and 3 times of dosage algae group had an extremely signifi.cant lower apoptosis at 7 days of administration （P 〈 0.01 ）, and the apoptosis of these two groups were significantly lower than that of pure higher iodine group （P〈 0.05）. At 28 days of administration, the number of apoptotic thyrocytes was markedly lower in normal control group than other four groups （P 〈 0.05-0.01）, and also significantly lower in pure higher iodine group than conventional dosage algae group （P 〈 0.05）.（2）Expressions of Fas, FasL and Bcl-2： Compared with model group, the conventional dosage algae group and 3 times of dosage algae group had a significant lower expression of Fas at 7 days of administration （P 〈 0.05）. The expression of FasL in pure higher iodine group and 3 times of dosage algae group was lower than that of model group （P 〈 0.05）. The expression of Bcl-2 in the conventional dosage algae group was significantly higher than that of model group （P 〈 0.05）. At 28 days of administration, the expression of Fas in pure higher iodine group and 3 times of dosage algae group was significantly lower than that of model group （P 〈 0.05）. The expression of Bcl-2 was significantly higher in pure higher iodine group, the conventional dosage algae group and 3 times of dosage algae group compared with model group （P 〈 0.05）. CONCLUSION： Administrations of algae with iodine excess for 28 days can cause the damnification of thyroid follicular epithelium in iodine deficiency rats. Fas, FasL and Bcl-2 are likely to induce apoptosis.