Melatonin: Nature's most versatile biological signal?
Seithikurippu R. Pandi-Perumal,V. Srinivasan,Georges J.M. Maestroni,Daniel P. Cardinali,Burkhard Poeggeler,Rüdiger Hardeland +5 more
TLDR
Melatonin is principally secreted at night and is centrally involved in sleep regulation, as well as in a number of other cyclical bodily activities, and its sleep-facilitating properties have been found to be useful for treating insomnia symptoms in elderly and depressive patients.Abstract:
Melatonin is a ubiquitous molecule and widely distributed in nature, with functional activity occurring in unicellular organisms, plants, fungi and animals. In most vertebrates, including humans, melatonin is synthesized primarily in the pineal gland and is regulated by the environmental light/dark cycle via the suprachiasmatic nucleus. Pinealocytes function as 'neuroendocrine transducers' to secrete melatonin during the dark phase of the light/dark cycle and, consequently, melatonin is often called the 'hormone of darkness'. Melatonin is principally secreted at night and is centrally involved in sleep regulation, as well as in a number of other cyclical bodily activities. Melatonin is exclusively involved in signaling the 'time of day' and 'time of year' (hence considered to help both clock and calendar functions) to all tissues and is thus considered to be the body's chronological pacemaker or 'Zeitgeber'. Synthesis of melatonin also occurs in other areas of the body, including the retina, the gastrointestinal tract, skin, bone marrow and in lymphocytes, from which it may influence other physiological functions through paracrine signaling. Melatonin has also been extracted from the seeds and leaves of a number of plants and its concentration in some of this material is several orders of magnitude higher than its night-time plasma value in humans. Melatonin participates in diverse physiological functions. In addition to its timekeeping functions, melatonin is an effective antioxidant which scavenges free radicals and up-regulates several antioxidant enzymes. It also has a strong antiapoptotic signaling function, an effect which it exerts even during ischemia. Melatonin's cytoprotective properties have practical implications in the treatment of neurodegenerative diseases. Melatonin also has immune-enhancing and oncostatic properties. Its 'chronobiotic' properties have been shown to have value in treating various circadian rhythm sleep disorders, such as jet lag or shift-work sleep disorder. Melatonin acting as an 'internal sleep facilitator' promotes sleep, and melatonin's sleep-facilitating properties have been found to be useful for treating insomnia symptoms in elderly and depressive patients. A recently introduced melatonin analog, agomelatine, is also efficient for the treatment of major depressive disorder and bipolar affective disorder. Melatonin's role as a 'photoperiodic molecule' in seasonal reproduction has been established in photoperiodic species, although its regulatory influence in humans remains under investigation. Taken together, this evidence implicates melatonin in a broad range of effects with a significant regulatory influence over many of the body's physiological functions.read more
Citations
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Melatonin as an antioxidant: under promises but over delivers.
Russel J. Reiter,Juan C. Mayo,Dun Xian Tan,Rosa M. Sainz,Moisés Alejandro Alatorre-Jiménez,Lilian Qin +5 more
TL;DR: It is the current feeling of the authors that, in view of the widely diverse beneficial functions that have been reported for melatonin, these may be merely epiphenomena of the more fundamental, yet‐to‐be identified basic action(s) of this ancient molecule.
Journal ArticleDOI
Melatonin as a natural ally against oxidative stress: a physicochemical examination
TL;DR: In this article, a review summarizes the current progress in understanding the physicochemical insights related to the free radical-scavenging activity of melatonin and concludes that melatonin efficiently protects against oxidative stress by a variety of mechanisms.
Journal ArticleDOI
Melatonin—A pleiotropic, orchestrating regulator molecule
Rüdiger Hardeland,Daniel P. Cardinali,Venkatramanujam Srinivasan,D. Warren Spence,Gregory M. Brown,Seithikurippu R. Pandi-Perumal +5 more
TL;DR: Control of electron flux, prevention of bottlenecks in the respiratory chain and electron leakage contribute to the avoidance of damage by free radicals and seem to be important in neuroprotection, inflammatory diseases and, presumably, aging.
Journal ArticleDOI
Physiological effects of melatonin: role of melatonin receptors and signal transduction pathways.
Seithikurippu R. Pandi-Perumal,Ilya Trakht,Venkataramanujan Srinivasan,D. Warren Spence,Georges J.M. Maestroni,Nava Zisapel,Daniel P. Cardinali +6 more
TL;DR: The evidence concerning melatonin receptors and signal transduction pathways in various organs is reviewed and their relevance to circadian physiology and pathogenesis of certain human diseases, with a focus on the brain, the cardiovascular and immune systems, and cancer is considered.
Journal ArticleDOI
Circadian genes, rhythms and the biology of mood disorders.
TL;DR: In this review, the evidence linking circadian rhythms and mood disorders, and what is known about the underlying biology of this association, is presented.
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