Weekley Claire M, Shanu Anu, Aitken Jade B, Vogt Stefan, Witting Paul K, Harris Hugh H
School of Chemistry and Physics, The University of Adelaide, SA 5005, Australia.
Metallomics. 2014 Sep;6(9):1602-15. doi: 10.1039/c4mt00088a.
Dietary selenium has been implicated in the prevention of cancer and other diseases, but its safety and efficacy is dependent on the supplemented form and its metabolites. In this study, X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (XFM) have been used to investigate the speciation and distribution of Se and Cu in vivo. In kidneys isolated from rats fed a diet containing 5 ppm Se as selenite for 3 weeks, Se levels increased 5-fold. XFM revealed a strong correlation between the distribution of Se and the distribution of Cu in the kidney, a phenomenon that has previously been observed in cell culture (Weekley et al., JBIC, J. Biol. Inorg. Chem., 2014, DOI: 10.1007/s00775-014-1113-x). However, X-ray absorption spectra suggest that most of the Se in the kidney is found as Se-Se species, rather than Cu-bound, and that most of the Cu is bound to S and N, presumably to amino acid residues in proteins. Furthermore, SOD1 expression did not change in response to the high Se diet. We cannot rule out the possibility of some Cu-Se bonding in the tissues, but our results suggest mechanisms other than the formation of Cu-Se species and SOD1 upregulation are responsible for the highly correlated distributions of Se and Cu in the kidneys of rats fed high selenite diets.
膳食硒与癌症及其他疾病的预防有关，但其安全性和有效性取决于所补充的形式及其代谢产物。在本研究中，X射线吸收光谱法（XAS）和X射线荧光显微镜法（XFM）已被用于研究体内硒和铜的形态及分布。在喂食含5 ppm亚硒酸盐的饲料3周的大鼠分离出的肾脏中，硒水平增加了5倍。XFM显示肾脏中硒的分布与铜的分布之间存在很强的相关性，这一现象先前在细胞培养中已被观察到（Weekley等人，《欧洲无机化学杂志》，《生物无机化学杂志》，2014年，DOI：10.1007/s00775-014-1113-x）。然而，X射线吸收光谱表明，肾脏中的大部分硒是以硒-硒物种的形式存在，而非与铜结合，并且大部分铜与硫和氮结合，推测是与蛋白质中的氨基酸残基结合。此外，超氧化物歧化酶1（SOD1）的表达并未因高硒饮食而改变。我们不能排除组织中存在一些铜-硒键合的可能性，但我们的结果表明，除了形成铜-硒物种和上调SOD1之外，其他机制才是喂食高亚硒酸盐饮食的大鼠肾脏中硒和铜高度相关分布的原因。
