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目的 评价硒在前列环素生物合成中的作用机制。方法 用低硒饲料、补硒饲料和常规饲料饲养雄性大鼠 1 4周后 ,测定血液和某些组织中硒、前列环素 ( PGI2 )、血栓素 ( TXA2 )和脂质过氧化物 ( LPO)的含量 ,谷胱甘肽过氧化物酶 ( GSH- Px)活性及前列腺素内过氧化物合成酶( PGHS)的过氧化物酶活性 ,并采用 RNA折叠程序对 3个前列环素合成酶 ( PGIS)基因 3 非翻译区 ( UTR)的二级结构进行计算机预测 ,与已知的 39个真核生物硒蛋白基因的硒代半胱氨酸插入序列 ( SECIS)进行比较。结果 低硒大鼠血浆 PGI2 浓度、血和组织中硒含量及 GSH- Px活性显著下降 ,LPO水平升高 ,但三组之间血浆 TXA2 水平和组织中 PGHS-过氧化物酶活性均无显著差异 ,在 PGIS基因中未见到硒蛋白所特有的 SECIS。结论 PGIS可能不是硒酶 ,硒可能是通过 GSH-Px或其他硒蛋白抑制过氧化物的产生而影响 PGI2 的合成
Objective To evaluate the mechanism of selenium in prostacyclin biosynthesis. Methods Sera, PGI2, TXA2 and LPO in blood and some tissues were measured after 14 weeks of feeding male rats with low-selenium diet, selenium-supplemented diet and conventional diet. ), Glutathione peroxidase (GSH-Px) activity and peroxidase activity of prostaglandin endoperoxide synthase (PGHS) were measured. The activities of three prostacyclin synthase (PGIS) gene 3 untranslated region (UTR) was predicted by computer and compared with the selenomethionine insertion sequence (SECIS) of 39 eukaryotic selenoprotein genes. Results The levels of plasma PGI2, selenium and GSH-Px activity in blood and tissues, and LPO levels in selenium-deficient rats decreased significantly, but there was no significant difference in plasma TXA2 level and PGHS-peroxidase activity between the three groups , No SECIS specific to selenoprotein was found in the PGIS gene. Conclusion PGIS may not be selenase. Selenium may affect the synthesis of PGI2 by inhibiting the production of peroxides by GSH-Px or other selenoproteins