Selenium, the thyroid, and the endocrine system.

Area of Science:

• Endocrinology
• Nutritional Biochemistry
• Molecular Biology

Background:

• New selenocysteine-containing proteins reveal links between selenium (Se), iodine, and hormone networks.
• Selenoproteins are vital for protecting thyrocytes during thyroid hormone synthesis.
• Endocrine tissues exhibit higher Se concentrations compared to other organs.

Purpose of the Study:

• To explore the intricate relationship between selenium, iodine, and the endocrine system.
• To elucidate the role of selenoproteins in thyroid hormone homeostasis and cellular protection.
• To understand the impact of Se levels on various endocrine functions and reproductive health.

Main Methods:

• Analysis of newly identified selenocysteine-containing proteins.
• Investigation of Se metabolism and its accumulation in endocrine tissues.
• Comparative genomic analysis of selenoprotein genes across different species.

Main Results:

• Selenoproteins protect thyrocytes from hydrogen peroxide and regulate thyroid hormone levels.
• Se depletion and repletion significantly affect Se levels in endocrine and reproductive organs.
• Selenoproteins link Se metabolism to transcriptional regulation via redox-sensitive nuclear receptors.
• Se influences bone metabolism, pancreatic and adrenal gland function, and spermatogenesis.
• Se excess may negatively impact ovarian function.

Conclusions:

• Selenium is essential for maintaining the function of the endocrine system, including thyroid, adrenal, and reproductive organs.
• Selenoprotein expression and activity are modulated by hormones and growth factors, and vice versa.
• Adequate Se supply is critical for spermatogenesis, while excess Se can be detrimental to ovarian function.