硒在前列环素生物合成中作用机制的研究

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

STUDY ON REGULATION MECHANISM OF PROSTACYCLIN SYNTHESIS BY SELENIUM

Objective:[WT5BZ]To evaluate the regulation mechanism of prostacyclin(PGI 2) synthesis by selenium (Se). [WT5FZ]Methods:[WT5BZ]Male Wistar rats were fed Se deficient diet, Se supplemented diet and stock diet for 14 weeks respectively. The levels of Se, PGI 2, TXA 2 and lipid peroxide (LPO), and activities of glutathione peroxidase (GSH Px), prostaglandin endoperoxide synthase peroxidase (PGHS Px) in blood and some tissues were determined. The predicted secondary structures of 3untranslated region (UTR) of 3 PGI 2 synthase genes (human, bovine and rat) were compared with the selenoproteine insertion sequences(SECIS) elements in 3UTR of 39 well known selenoprotein genes by computer RNA folding program. [WT5FZ]Rusults:[WT5BZ] The plasma PGI 2, Se and GSH Px activity in blood and liver of Se deficient rats were decreased significantly. LPO in plasma and liver were increased significantly, but no remarkable differences in plasma TXA 2 and tissue PGHS Px activities. The specific SECIS element belonging to selenoprotein gene was not found in 3UTR of PGI 2 synthase mRNAs. [WT5FZ]Conclusion:[WT5BZ] PGI 2 synthase may not be a selenoenzyme. The regulation of PGI 2 synthesis by Se may be due to inhibited lipid peroxidation by GSH Px or/and other selenoprotein. [WT5”FZ]