Thyroid hormone and myocardial mitochondrial biogenesis.

Mitochondria have been central in the development of some of the most important ideas in modern biology. Since the discovery that mitochondria have its own DNA and specific mutations and deletions were found in association with neuromuscular and heart diseases, as well as in aging, an extraordinary number of publications have followed, and the term mitochondrial medicine was coined. Recently, it has been found that thyroid hormone (TH) stimulates cardiac mitochondrial biogenesis increasing myocardial mitochondrial mass, mitochondrial respiration, oxidative phosphorylation (OXPHOS), enzyme activities, mitochondrial protein synthesis (by stimulation in a T3-dependent manner), cytochrome, phospholipid and mtDNA content. Also, TH therapy may modulate cardiac mitochondrial protein-import apparatus. To identify the sequence of events, molecules and signaling pathways that is activated by TH affecting mitochondrial structure, biogenesis and function further research is warranted.