Identification of the biliary selenium metabolite and the biological significance of selenium enterohepatic circulation
Identification of the biliary selenium metabolite and the biological significance of selenium enterohepatic circulation
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DOI：
10.1039/c9mt00274j
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发表时间：
2020-02-01
期刊：
影响因子：
3.4
通讯作者：
Ogra, Yasumitsu
中科院分区：
文献类型：
--
作者：
Takahashi, Kazuaki;Ogra, Yasumitsu
虽然硒（Se）主要通过尿液排出，但据报道，一种未知的硒代谢物也通过胆汁排出。当我们给大鼠服用硒代蛋氨酸（SeMet）、硒氰酸盐或亚硒酸盐时，给药10分钟后检测到一种常见的胆道硒代谢物。来自SeMet的硒代谢物数量少于来自硒氰酸盐和亚硒酸盐两种无机硒化合物的硒代谢物数量，这表明甲基化的有机硒化合物（即SeMet）的转化效率低于无机硒化合物。通过lc -电感耦合质谱（ICP-MS）和LC-ESI-Q/TOF两种质谱方法，具体鉴定出胆道中常见的硒代谢物为硒二谷胱甘肽（selenodigutathione, GSSeSG）。排胆大鼠尿硒水平低于假手术大鼠。此外，排胆大鼠尿液和胆汁中的硒含量与假手术大鼠尿液中的硒含量相当。这些结果表明，胆道硒代谢物GSSeSG在肠道中被重新吸收，最终通过尿液排出体外。发生肠肝循环以维持体内硒的状态。
Although selenium (Se) is mainly excreted in urine, it has been reported that an unknown Se metabolite is excreted in bile. When we administered selenomethionine (SeMet), selenocyanate or selenite to rats, a common biliary selenometabolite was detected 10 min after administration. The amount of the selenometabolite originating from SeMet was less than that originating from the two inorganic Se compounds, selenocyanate and selenite, suggesting that the transformation from the methylated organic selenocompound, i.e., SeMet, was less efficient than that from the inorganic Se compounds. The common biliary selenometabolite was concretely identified as selenodiglutathione (GSSeSG) by two types of mass spectrometry, i.e., LC-inductively coupled mass spectrometry (ICP-MS) and LC-ESI-Q/TOF. The bile-drained rats had lower urinary Se levels than the sham-operated rats. In addition, the Se amounts in urine plus bile of the bile-drained rats were comparable to the Se amount in the urine of the sham-operated rats. These results suggest that the biliary selenometabolite, GSSeSG, was reabsorbed in the gut and finally excreted in urine. Enterohepatic circulation occurs to maintain Se status in the body.