硒碘联合作用对机体甲状腺激素代谢的影响机制探讨

用克山病病区粮以及分别加 Se 或/和加 I 喂饲大鼠,并观察机体甲状腺激素的代谢变化。结果发现,缺 I 可显著降低循环和肝脏的 T_4水平,循环总 T_3受 Se、I 影响不十分明显,但 FT_3变化较大。缺 Se 使肝 I 型5′-脱碘酶活性下降,并使肝 T_3生成减少,但因此引起 T_4堆积的现象只能在缺 Se加 I 组中出现。甲状腺组织的甲状腺激素水平因缺 I 而减少,但缺 Se 并未使其进一步下降,反而有较大幅度的升高,且同时使甲状腺肿胀加剧。循环促甲状腺激素(TSH)有相对稳定循环T_3水平的作用。TSH 与 T_4负相关。研究提示,不同 Se、I 营养状况对循环和组织甲状腺激素代谢影响不同,肝组织内源性甲状腺激素受 Se 水平影响较大。

Effect of combined iodine and selenium deficiency on thyroid hormone metabolism in rats

The effects of combined iodine and selenium deficiency (Se~-I~-),single deficiency of iodine or selenium (Se~+I~-,Se~-I~+) and no deficiency (Se~+I~+) on the metabolism of thyroid hormone in rats were compared.In the Se~-I~- group,plasma thyroxin (T_4),free T_4 (FT_4) were significantly lower,plasma thyroid-stimulating hormone (TSH) was significantly higher than that in Se~+I~+ and Se~-I~+ rats,but not different from Se~+I~- rats.Iodine supplementation increased the plasma T_4 level in the two I~+ groups,T_4 level in Se~-I~+ group was the highest.Plasma T_3 and FT_3 were not different significantly in all the four groups,but Se supplementa- tion increased the liver T_3 level with an increase in type I 5'-deiodinase activity in the two Se~+ groups.How- ever,Se supplementation significantly lowered the liver T_4 level in the I~+ groups.Thyroidal T_4 and T_3 were higher in the two I~+ group than the two I~- groups,with the lowest in Se~+、I~-.This study indicates that Se deficiency plays an important role in thyroid hormone metabolism,especially via liver and thyroid.