CRIM 2653 Lecture Notes - Lecture 40: Basal Metabolic Rate, Thyroid, Methimazole
23 May 2020
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Endogenous ligand: 3,5,3"-triiodothyronine (t3); l-thyroxine (t4) is less active (t3 is a precursor to t4 and is more potent) Function: maintains basal metabolic rate, critical for normal development, especially of. Tr 1 is widely expressed and especially high expression in cardiac and skeletal muscles. Tr 2 is widely expressed but unable to bind hormone. Tr 1 is predominantly in the brain, liver and kidney. Agonists: levothyroxine (t4); mixtures of t3 and t4 (used for the treatment of hypothyroidism, one of the most highly prescribed drugs in america) Other notes: propylthiouracil and methimazole inhibit the production of thyroid hormone and therefore have anti-thyroid effects but are not direct antagonists of the receptor. Hypothyroidism: failure of the thyroid gland to produce enough thyroid hormone. Symptoms: tiredness, depression, weight gain among others; in children it may result in growth and intellectual development delays. Thyroid hormones are carefully monitored in pregnant women to ensure sufficient levels for fetus.
