Melatonin and cardiac pathophysiology

Melatonin, an indole produced in several organs but most notably in the pineal gland, has a variety of effects that influence cardiac pathophysiology. Herein, we summarize the findings that illustrate the ability of melatonin to attenuate the severity of hypertension, limit myocardial damage, improve the function of the ischemic-reperfused heart, protect the heart from the toxicity of anthracycline drugs and from an immunosuppressant drug (cyclosporine A), and reduce cardiac hypertrophy and the associated pathophysiology caused by hyperthyroidism. The protective actions of melatonin at the level of the heart probably involve membrane melatonin receptors that exist on cardiomyocytes, in addition functions of melatonin as an antioxidant that are not receptor mediated. Whereas studies to date have been performed primarily in experimental animals, the uncommonly low toxicity of melatonin warrants tests of its utility in humans in cases of cardiac pathophysiology. Heart Metab. 2009;44:31–34.