不同碘营养状态对克汀大鼠脑内T4 5′-和5-脱碘酶活性的影响

目的研究不同碘营养状态下克汀大鼠脑内T4 5′-和5-脱碘酶活性的变化.方法复制Wistar克汀大鼠,通过饮水中含碘量不同分为低碘组、适碘组、高碘组、正常对照组,每组2或3窝(31～42只),选用20 d龄的仔鼠进行实验,测定4组动物模型甲状腺功能状态及脑T4 5′-和5-脱碘酶活性.结果低碘组TT4和FT4均低于正常对照组,均为正常对照组的3.5% ,FT3高于正常对照组74.0%;适碘组TT4和FT4高于正常对照组14.5%和27.7%;高碘组TT4和FT4均低于正常对照组,仅为正常对照组的61.86%和62.0%,TT3低于正常对照组,FT3显著高于正常对照组84.9%.低碘组脑组织中T45′-脱碘酶活性相当于每克组织每小时(1.95±0.32 ) ngT3/μgT4,显著高于正常对照组(1.59±0.23),5-脱碘酶活性相当于每克组织每小时(1.38±0.21) ngrT3/μgT4,低于正常对照组(2.02±0.26),高碘组T45′-和5-脱碘酶活性每克组织每小时(1.12±0.19)ngT3/μgT4和(1.73±0.36)ngrT3/μgT4,低于正常对照组.结论 5′-脱碘酶活性在低碘时活性升高,在高碘时活性降低;5-脱碘酶在低碘和高碘时活性均降低.

Effects of various iodin-nutritional on activity of T4 5'-and 5-deiodinase in rat brain

OBJECTIVE: To investigate the changing of T4 5'-and 5-deiodinase within rat brain under various iodin-nutritional states. METHODS: Animal model of iodine-deficiency rat was performed and the rats were divided into 4 groups by the intake of iodine-nutrition, and then killed at an age of 20 days. The thyroid hormones level in serum was measured by ELISA and the activity of T(4) 5'-and 5-deiodinase within brain was analyzed. RESULTS: In less-iodine (LI) group,TT4 and FT4 were accounting for 3.5% of the neutral-iodine (NI) group's, and FT3 was 174.0% of NI group's (P < 0.05). In NI group,TT4 and FT4 were 114.5% and 127.7% of NI group's (P < 0.05). In high-iodine (HI) group, TT4 and FT4 were 61.86% and 62.0% of NI group's, and FT3 was 184.9% of NI group's (P < 0.05). In LI group, the activity of T4 5'-deiodinase tissue of per gram (1.95 +/- 0.32) ngT3.microgT4(-1).h was significantly higher than that of NI group (P < 0.05), and the activity of 5-deiodinase (1.38 +/- 0.21) ngrT3.microg T4(-1).h(-1) is significantly less than that of NI group (1.59 +/- 0.23) (P < 0.05). In HI group the activity of T4 5'-and 5-deiodinase tissue of per gram (1.12 +/- 0.19 and 1.73 +/- 0.36) ngrT3.microgT4(-1).h(-1)was significantly less than that of NI group (P < 0.05). CONCLUSION: The activity of T4 5'-deiodinase in iodine deficiency heightens and that in iodine excess is debased, the activity of T4 5-deiodinase in iodine deficiency and in iodine excess is debased.