Antiaging Hormone
Studies linking melatonin loss to age-related phenomena and the case for melatonin as an antiaging substance have been highlighted in review articles.[9,129] One proponent of this hypothesis suggests that "the Melatonin Deficiency Syndrome is perhaps the basic mechanism through which aging changes can be explained."[129] Indeed, some believe that the data thus far support the possibility that supplemental melatonin may be beneficial.[130]
An experimental study found significant declines in plasma melatonin levels in aged ring doves.[131] In addition, the capacity of the animals for ingestion and destruction of Candida albicans and phagocytosis was reduced by aging and restored by exogenous administration of melatonin.
Melatonin levels decline with age in humans,[132] and the nocturnal melatonin peak is almost completely lost.[133] Because of the close reciprocal relation of melatonin and corticoids, this loss of melatonin rhythmicity may be responsible for the pituitary/adrenal axis disinhibition that has been described as a characteristic of aging. The adrenals of elderly humans are apparently hypersensitive to adrenocorticotropic hormone, and midnight corticoid levels (low in youth) are markedly elevated in old age.[134] The effects of melatonin on both the release of corticoids and their peripheral effects, the pathogenic conditioning influence of corticoid excess, and the phasic inhibitory influence of melatonin on the pituitary/adrenal axis have been discussed. Modification of corticoid-related phenomena could explain much of melatonin's apparent antiaging and other beneficial actions.
Despite the evidence linking lowered levels of melatonin with aging, the decline may not be so dramatic in reality. That is why melatonin cannot be unequivocally recognized as a substance that delays aging, although some of its actions may be beneficial to the process of aging.[135]
Blindness (which increases melatonin levels by virtue of effective constant darkness) and melatonin administration both increase the life span of rats.[130,136] However, in many cases melatonin levels are free-running, and in one study, low doses (0.5 mg) of melatonin entrained a blind person with free-running melatonin rhythms.[137]
© 2004 Medscape
Cite this: The Therapeutic Potential of Melatonin: A Review of the Science - Medscape - Apr 14, 2004.
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