Posts Tagged ‘Selenocysteine’

Selenium and the control of thyroid hormone metabolism.

Friday, July 1st, 2011

-:: This Abstract is posted here for posterity and archival purposes only ::-

Thyroid. 2005 Aug;15(8):841-53.
Selenium and the control of thyroid hormone metabolism.
Köhrle J.

Institut für Experimentelle Endokrinologie und Endokrinologisches Forschungs-Centrum der Charité EnForCé, Charité Universitätsmedizin Berlin, Berlin, Germany. josef.koehrle@charite.de

Abstract

Thyroid hormone synthesis, metabolism and action require adequate availability of the essential trace elements iodine and selenium, which affect homeostasis of thyroid hormone-dependent metabolic pathways.

The three selenocysteine-containing iodothyronine deiodinases constitute a novel gene family. Selenium is retained and deiodinase expression is maintained at almost normal levels in the thyroid gland, the brain and several other endocrine tissues during selenium deficiency, thus guaranteeing adequate local and systemic levels of the active thyroid hormone T(3).

Due to their low tissue concentrations and their mRNA SECIS elements deiodinases rank high in the cellular and tissue-specific hierarchy of selenium distribution among various selenoproteins.

While systemic selenium status and expression of abundant selenoproteins (glutathione peroxidase or selenoprotein P) is already impaired in patients with cancer, disturbed gastrointestinal resorption, unbalanced nutrition or patients requiring intensive care treatment, selenium-dependent deiodinase function might still be adequate.

However, disease-associated alterations in proinflammatory cytokines, growth factors, hormones and pharmaceuticals modulate deiodinase isoenzyme expression independent from altered selenium status and might thus pretend causal relationships between systemic selenium status and altered thyroid hormone metabolism.

(more…)

Study: The impact of iron and selenium deficiencies on iodine and thyroid metabolism: biochemistry and relevance to public health.

Friday, July 1st, 2011

-:: This Abstract is posted here for posterity and archival purposes only ::-

Thyroid. 2002 Oct;12(10):867-78.

The impact of iron and selenium deficiencies on iodine and thyroid metabolism: biochemistry and relevance to public health.

Zimmermann MB, Köhrle J.

Laboratory for Human Nutrition, Swiss Federal Institute of Technology, Zürich, Switzerland. Michael.zimmermann@ilw.agrt.ethz.ch
Abstract

Several minerals and trace elements are essential for normal thyroid hormone metabolism, e.g., iodine, iron, selenium, and zinc. Coexisting deficiencies of these elements can impair thyroid function.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
An automatic insert of some related ads:

Thanks for your patronage. Article continues below:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Iron deficiency impairs thyroid hormone synthesis by reducing activity of heme-dependent thyroid peroxidase. Iron-deficiency anemia blunts and iron supplementation improves the efficacy of iodine supplementation.

Combined selenium and iodine deficiency leads to myxedematous cretinism. The normal thyroid gland retains high selenium concentrations even under conditions of inadequate selenium supply and expresses many of the known selenocysteine-containing proteins. Among these selenoproteins are the glutathione peroxidase, deiodinase, and thioredoxine reductase families of enzymes.

Adequate selenium nutrition supports efficient thyroid hormone synthesis and metabolism and protects the thyroid gland from damage by excessive iodide exposure.

In regions of combined severe iodine and selenium deficiency, normalization of iodine supply is mandatory before initiation of selenium supplementation in order to prevent hypothyroidism.

(more…)



Disclaimer: I must say this: The information presented herein is for informational purposes only. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements, making dietary changes, or before making any changes in prescribed medications.
All posts are strictly opinions meant to foster debate, education, comment, teaching, scholarship and research under the "fair use doctrine" in Section 107 of U.S. Code Title 17. No statement of fact is made and/or should be implied. Please verify all the articles on this site for yourself. The Information found here should in no way to be construed as medical advice. If You have a health issue please consult your professional medical provider. Everything here is the authors own personal opinion as reported by authors based on their personal perception and interpretation as a part of authors freedom of speech. Nothing reported here should be taken as medical advice, diagnosis or prescription; medical advice should only be taken from your health care provider. Consume the information found on this web site under your own responsibility. Please, do your own research; reach your own conclusions, and take personal responsibility and personal control of your health.