Melatonin in cardiovascular disease.

This editorial refers to "Cardiovascular effects of melatonin receptor agonists". The hormone melatonin is synthesized primarily in the pineal gland, retina, several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Based on the data available, the last 18 years indicate that melatonin influences multiple factors of the cardiovascular function. Multiple evidences reveal that the rhythmicity of melatonin has a crucial role in a variety of cardiovascular pathophysiological processes including anti-inflammatory, antioxidant, anti-hypertensive and possibly as an antilipidemic function. Melatonin receptors receive and transduce melatonin's message to influence daily and seasonal rhythms of physiology. The melatonin message is translated through the interaction between the melatonin receptors (MT1 and MT2) and its coupling to G proteins, which are potential therapeutic targets in disorders ranging from insomnia, circadian sleep disorders, depression and cardiovascular diseases. Based on the data available, melatonin seems to have cardioprotective properties via its direct free radical scavenger activity. Melatonin efficiently interacts with several reactive oxygen species (receptor-independent actions). Collectively, these protective actions of melatonin may have potential clinical applicability for individuals with cardiovascular disease.