Triiodothyronine is a thyroid hormone. It is metabolically active hormone that is produced from T4. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate, increases the basal metabolic rate and, thus, increases the body's oxygen and energy consumption, stimulates the production of RNA Polymerase I and II, potentiates the effects of the b-adrenergic receptors on the metabolism of glucose, stimulates the breakdown of cholesterol and increases the number of LDL receptors. It affects the lungs and influences the postnatal growth of the central nervous system. It stimulates the production of myelin, the production of neurotransmitters, and the growth of axons. It is also important in the linear growth of bones, may increase serotonin in the brain, in particular in the cerebral cortex, and down-regulate 5HT-2 receptors, used to treat Wilson's syndrome. |