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用不同硒含量的半合成饲料(试验组饲料含硒0.005ppm,对照组饲料含硒0.105ppm),饲喂断奶的Hooded Lister大鼠6周,研究了在不同硒营养状态下,大鼠肝、肾、脑、垂体及褐脂中5′-脱碘酶活性的变化。试验进行2、4、6周后,试验组大鼠组织中GSH-Px及5′-脱碘酶活性比对照组显著降低。按组织中GSH-Px及5′-脱碘酶活性下降幅度的大小,可把各组织分别排序为:肝>肾>褐脂>垂体>脑和肝>肾>褐脂>脑>垂体。硒耗竭2、4、6周后,肝脏GSH-Px活性下降94％、99％、及99.2％,肝脏5′-脱碘酶活性下降的幅度分别为62％80％及90％。硒调节5′-脱碘酶活性可能因为硒是Ⅰ型脱碘酶的辅助因子;而Ⅱ型脱碘酶活性的变化则可能是缺硒导致组织局部T_4水平升高的间接作用。硒缺乏降低5′-脱碘酶活性会导致大鼠循环T_4水平升高,而循环T_3水平降低。
Weaned Hooded Lister rats were fed with semi-synthetic feed with different selenium contents (0.005ppm selenium in test group and 0.105ppm selenium in control group) for 6 weeks. The effects of selenium, Changes of 5’-deiodinase activity in kidney, brain, pituitary and brown fat. After 2, 4 and 6 weeks of the experiment, the activities of GSH-Px and 5’-deiodinase in the experimental group were significantly lower than those in the control group. According to the magnitude of GSH-Px and 5’-deiodinase activity in tissues, the tissues can be sorted as: liver> kidney> brown fat> pituitary> brain and liver> kidney> brown fat> brain> pituitary. After 2,4 and 6 weeks of selenium depletion, hepatic GSH-Px activity decreased by 94%, 99%, and 99.2%, respectively, and liver 5’-deiodinase activity decreased by 62% and 90%, respectively. Selenium may regulate 5’-deiodinase activity because selenium is a cofactor for type I deiodinase, while changes in type II deiodinase activity may be an indirect effect of selenium deficiency leading to elevated tissue T 4 levels. Selenium deficiency reduces 5’-deiodinase activity will lead to elevated circulating T_4 levels in rats, while circulating T_3 levels decreased.