硒干预过量碘致甲状腺滤泡上皮细胞组织蛋白酶活性下降的作用

THE INTERVENTION EFFECT OF SELENIUM ON DECREASE OF CATHEPSIN B,D ACTIVITIES OF THYROID FOLLICULAR EPITHELIAL CELL LINE INDUCED BY IODINE EXCESS

目的:探讨硒干预过量碘对甲状腺滤泡上皮细胞组织蛋白酶活性下降与胶质潴留的作用及其机制。方法:FRTL细胞培养于Kaighn’s改良的Ham’sF-12培养基。①测定组织蛋白酶B和D(CB、CD)活性。细胞分组:正常对照组:培养基内不加碘或硒;过量碘组:培养基内加入50mmol/L碘化钾(KI);过量碘加硒组:培养基内加入50mmol/LKI和硒浓度分别为0.1、0.2、0.5、1.0、2.0和5.0μmol/L的亚硒酸钠(Na2SeO3)。②测定CB和CDmRNA的水平。细胞分组同上,但过量碘补硒组只加0.1μmol/L的硒。收集细胞,荧光定量PCR测定CB和CDmRNA水平。结果:0.1～0.5μmol/L补硒组CB、CD活性较过量碘组显著升高(p﹤0.05)。补充硒可以升高由50mmol/L碘导致的CB、CDmRNA水平下降。结论:补充0.1～0.5μmol/L剂量范围的硒可使过量碘导致的CB、CD损伤好转,这也是硒可缓解胶质潴留的原因之一。

Objective： To detect the damage of excessive iodine on the activities and mRNA of cathepsin B and D and observe the effects of selenium intervention. Method： Thyroid follicular epithelial cell line FRTL was cultured in Kaighn＇s modified Ham＇s F-12 medium. ① The cells were divided into 8 groups for detection of activities of cathepsin B and D （CB and CD）. The medium of NI group did not contain selenium or iodine, while EI group contained 50 mmol/L KI, and IS group contained 50mmol/L KI and different dosages of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 μmol/L selenium （sodium selenite）. ②The mRNA levels of cathepsin B and D were detected by real-time PCR. The medium of NI group and EI group was same as above, but IS group only contained 0.1μmol/L selenium besides 50mmol/L KI. Results： The activities of CB decreased in EI group （50mmol/L KI treated 12 h）, while CD decreased after 24 h and both activities were improved in IS groups with 0.1-0.5μmol/L selenium. The mRNA levels of CB and CD in EI group decreased, while in IS group were improved. Conclusion： Excessive iodine resulted in goiter through decreased levels of activities and mRNA of CB and CD. The intervention of selenium on goiter may induce its amelioration effect on decrease of CB and CD activities and the optimal dosage ranges from 0.1 μmol/L to 0.5μmol/L.