Thyroid hormone regulation of mitochondrial function. Comments on the mechanism of signal transduction

Thyroid hormone exerts two types of effect on mitochondria. The first of these is a rapid activation of respiration which takes place within minutes after hormone injection, and is preserved in isolated mitochondria. The second response occurs after 1 to several days of injection and leads to mitochondrial biogenesis and increases in mitochondria mass. The hormone signal for these two responses involves either triiodothyronine (T3)-responsive nuclear genes or a direct action of T3 at mitochondria binding sites.