Selenium

Is selenium intake associated with the presence of depressive symptoms among US adults? Findings from National Health and Nutrition Examination Survey (NHANES) 2011-2014

OBJECTIVES

This study aimed to examine the cross-sectional association between dietary and serum selenium measures and depressive symptoms among a nationally representative sample of US adults.

METHODS

Dietary selenium intake and serum selenium concentration were evaluated on 7725 adult participants from National Health and Nutrition Examination Survey (NHANES) 2011-2014. Participants' selenium intake, assessed by 24-h recall, was classified based on the recommended dietary allowance (dietary selenium intake ≥ 55 μg/d) and estimated average requirement (dietary selenium intake ≥ 45 μg/d) criteria. Serum selenium and depressive symptoms were assessed using inductively coupled plasma mass spectrometry and a patient health questionnaire or use of an antidepressant, respectively. Univariate and multivariate logistic regression, accounting for the complex survey design of NHANES, were employed to estimate the cross-sectional association between measures of selenium and the presence of depressive symptoms.

RESULTS

The median selenium concentration was 193.9 µg/L (interquartile range = 179.3-209.3). Approximately 8% of the participants met the case definition for depressive symptoms. Based on the recommended dietary allowance of selenium, participants not meeting the recommended dietary intake, compared with those meeting the requirement, had higher odds of depressive symptoms (odds ratio [OR] = 1.57, 95% confidence interval [CI]: 1.03-2.38). When analyzing by quintile of dietary selenium intakes, compared with the first quintile, participants in higher quintiles had significantly lower odds of depressive symptoms. However, based on quintiles of serum selenium and using the first quintile as referent category, except for quintile 3, results indicated a higher but not significant association (quintile 2 [OR = 1.08, 95% CI: 0.73-1.61], quintile 4 [OR = 1.17, 95% CI: 0.89-1.55], and quintile 5 [OR = 1.14, 95% CI: 0.83-1.58]). Power analysis indicated sufficient power. Notably, study participants had a very high serum selenium concentration. The findings, although not significant, between serum selenium concentrations and depressive symptoms had a U-shaped association, supported by the current literature.

CONCLUSIONS

Our study supports an inverse association between participants recommended dietary intake of selenium and depressive symptoms. Although results were not statistically significant for the association by quartile of serum selenium concentrations and depressive symptoms, a U-shaped association was identified.

Selenoproteins in human body: focus on thyroid pathophysiology

Selenium (Se) has a multilevel, complex and dynamic effect on the human body as a major component of selenocysteine, incorporated into selenoproteins, which include the selenocysteine-containing enzymes iodothyronine deiodinases. At the thyroid level, these proteins play an essential role in antioxidant protection and hormone metabolism. This is a narrative review based on PubMed/Medline database research regarding thyroid physiology and conditions with Se and Se-protein interferences. In humans, Se-dependent enzyme functions are best expressed through optimal Se intake, although there is gap in our knowledge concerning the precise mechanisms underlying the interrelation. There is a good level of evidence linking low serum Se to autoimmune thyroid diseases and, to a lesser extent, differentiated thyroid cancer. However, when it comes to routine supplementation, the results are heterogeneous, except in the case of mild Graves' orbitopathy. Autoimmune hypothyroidism is associated with a state of higher oxidative stress, but not all studies found an improvement of thyroid function after Se was introduced as antioxidant support. Meanwhile, no routine supplementation is recommended. Low Se intake is correlated with an increased risk of developing antithyroid antibodies, its supplementation decreasing their titres; there is also a potential reduction in levothyroxine replacement dose required for hypothyroidism and/or the possibility that it prevents progression of subclinical hypothyroidism, although not all studies agree. In thyroid-associated orbitopathy, euthyroidism is more rapidly achieved if the micronutrient is added to traditional drugs, while controls appear to benefit from the microelement only if they are deficient; thus, a basal assay of Se appears advisable to better select patients who need substitution. Clearly, further Se status biomarkers are required. Future introduction of individual supplementation algorithms based on baseline micronutrient levels, underlying or at-risk clinical conditions, and perhaps selenoprotein gene polymorphisms is envisaged.

Integrated analysis of microRNA and mRNA expression profiles in rats with selenium deficiency and identification of associated miRNA-mRNA network

Selenium deficiency is closely related with various type of cardiovascular disease. However, the miRNA-mRNA regulatory network in Selenium deficiency related cardiac change remains to be understand. In the present study, a reliable Selenium deficiency rat model was established and confirmed by pathological and biochemical examination. The mRNA and miRNA expression profiles were conducted by microarray technology. Gene Ontology (GO) Analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway Analysis was performed to investigate the function of targeted genes, and the relationship between miRNA and mRNA was studied by network analysis. A total of 4931 mRNAs and 119 miRNAs was differentially expressed between any two groups (control group, low-selenium group and selenium supplementation group). GO and KEGG pathway analysis of selected miRNAs target genes found that selenium deficiency was related to several different biological processes. Furthermore, a miRNA-mRNA regulatory network was conducted to illustrate the interaction of miRNAs and these targeted genes. In conclusion, our present study provides a new insight that potential molecular mechanism of Selenium deficiency was a multiply miRNAs and mRNA caused biological change.

The design, synthesis and evaluation of selenium-containing 4-anilinoquinazoline hybrids as anticancer agents and a study of their mechanism

We report the design, synthesis and evaluation of 2-chloro-N-methyl-N-(4-selenocyanatophenyl)quinazolin-4-amine and its analogues as anticancer agents and the mechanism study.

Response of Selenium and Selenogenome in Immune Tissues to LPS-Induced Inflammatory Reactions in Pigs

Circulating concentration of the essential trace element selenium (Se) was significantly lower in inflammatory disorders. Although Se plays physiological roles mainly through the function of 25 selenoproteins, the response of the selenogenome in immune tissues during inflammatory reactions remains unclear. The objective of this study was to determine the Se retention and selenogenome expression in immune tissues during the lipopolysaccharide (LPS)-induced inflammatory response in porcine. A total of 12 male pigs were randomly divided into two groups and injected with LPS or saline. After 4 h postinjection, blood samples were collected and pigs were euthanized. Pigs challenged with LPS had 36.8 and 16.6 % lower (P < 0.05) Se concentrations in the serum and spleen, respectively, than those injected with saline. Moreover, the activities of GPX decreased (P < 0.05) by 23.4, 26.6, and 30.4 % in the serum, thymus, and lymph node, respectively, in the pigs injected with LPS. Furthermore, the LPS challenge altered (P < 0.05) the mRNA expression of 14, 16, 10, and 6 selenoprotein genes in the liver, spleen, thymus, and lymph node, respectively. Along with 10 previously reported selenoprotein genes, the response of Txnrd2, Txnrd3, Sep15, Selh, Seli, Seln, Selo, Selt, Selx, and Sephs2 to inflammatory reaction in immune tissues were newly illustrated in this study. In conclusion, the LPS-induced inflammatory response impaired Se metabolism and was associated with dysregulation of the selenogenome expression in immune tissues.