大鼠脑中的硒蛋白

喂Ｗｉｓｔａｒ雄性大鼠以８种不同硒水平的饲料，２０周时每组处死大鼠６只，取其大脑。硒耗竭组再随机分为４组，饲以４种不同硒水平的饲料，分别于不同时间处死，动态观察各种硒蛋白的变化。实验结果表明：细胞内谷胱甘肽过氧化物酶（ｃＧＰＸ）、磷脂氢谷胱甘肽过氧化物酶（ＰＨＧＰＸ）和Ⅱ型脱碘酶（ＩＤⅡ）发挥正常活性所需的最低饲料硒水平分别为０．０５、０．０３和０．０１ｍｇ／ｋｇ，而硒蛋白Ｐ和硒蛋白Ｗ正常表达时所需的最低饲料硒水平分别为０．０１和０．０５ｍｇ／ｋｇ。硒耗竭后补硒时硒蛋白Ｐ和ＩＤⅡ最优先利用硒，ｃＧＰＸ和ＰＨＧＰＸ次之，硒蛋白Ｗ最后。提示在脑中硒蛋白Ｐ和ＩＤⅡ较其余３种硒蛋白更重要。

Selenoproteins in rat brain

Male Wistar rats fed with diets containing eight different levels of selenium(Se). Six rats in each group were killed after 20 weeks to obtain brains. The other 105 rats in the Se depleted group were then divided into four groups randomly and fed with diets containing four different levels of Se. The rats in these four groups were then killed at different time points to observe the kinetic change of selenoproteins. The lowest dietary Se required for reaching the plateau of the activities of cellular glutathione peroxidase (cGPX), phospholipid hydroperoxide glutathione peroxidase (PHGPX) and type II deiodinase (ID II) were 0.05, 0.03 and 0.01 mg/kg respectively. The lowest dietary Se required for reaching normal expression of selenoprotein P and selenoprotein W were 0.01 and 0.05 mg/kg respectively. While the rats were restored Se from diets supplemented with Se, the expression of selenoprotein P and type II deiodinase were in preference to PHGPX and cGPX, and the later two parameters were in preference to selenoprotein W. The results suggested that the function of selenoprotein P and ID II in brain were more important than the other three selenoproteins.