(Healthy) ageing: focus on iodothyronines.

Area of Science:

• Endocrinology
• Metabolism
• Aging Research

Background:

• Thyroid gland activity declines with age, yet T3 reserves persist, potentially regulating energy homeostasis.
• Traditional understanding of T3 action involves genomic pathways via thyroid hormone receptors (TRs).

Purpose of the Study:

• To critically assess the regulatory role of thyroid hormone reserves in energy homeostasis during aging.
• To explore the emerging non-genomic mechanisms of thyroid hormone action and their implications for aging.

Main Methods:

• Literature review of studies on thyroid hormone (T3) and its metabolites, focusing on genomic and non-genomic pathways.
• Analysis of research investigating the role of T3, T2, SIRT1, and AMPK in aging and metabolic diseases.

Main Results:

• Thyroid hormone (T3) and its metabolites are maintained during aging and may regulate energy balance.
• Non-genomic signaling pathways, distinct from TR-mediated transcription, are involved in thyroid hormone action.
• 3,5-diiodo-L-thyronine (T2) activates SIRT1, potentially improving healthy aging, while T3 might have opposing effects.

Conclusions:

• Thyroid hormones (T3, T2) and their signaling pathways (SIRT1, AMPK) are crucial for managing aging-associated metabolic issues like obesity and insulin resistance.
• Understanding non-genomic thyroid hormone actions offers new therapeutic targets for healthy aging and metabolic health.