Melatonin: Physiological Effects in Humans.

Claustrat B., Leston J.
Neurochirurgie, 2015

Abstract

Melatonin is a methoxyindole synthesized and secreted principally by the pineal gland at night under normal light/dark conditions. The endogenous rhythm of secretion is generated by the suprachiasmatic nuclei and entrained to the light/dark cycle. Light is able to either suppress or synchronize melatonin production according to the light schedule. The nycthohemeral rhythm of this hormone can be evaluated by repeated measurement of plasma or saliva melatonin or urine sulfatoxymelatonin, the main hepatic metabolite. The primary physiological function of melatonin, whose secretion adjusts to night length, is to convey information concerning the daily cycle of light and darkness to body structures. This information is used for the organisation of functions, which respond to changes in the photoperiod such as the seasonal rhythms. Seasonal rhythmicity of physiological functions in humans related to possible alteration of the melatonin message remains, however, of limited evidence in temperate areas under field conditions. Also, the daily melatonin secretion, which is a very robust biochemical signal of night, can be used for the organisation of circadian rhythms. Although functions of this hormone in humans are mainly based on correlations between clinical observations and melatonin secretion, there is some evidence that melatonin stabilises and strengthens coupling of circadian rhythms, especially of core temperature and sleep-wake rhythms. The circadian organisation of other physiological functions depend also on the melatonin signal, for instance immune, antioxidant defences, haemostasis and glucose regulation. The difference between physiological and pharmacological effects of melatonin is not always clear but is based upon consideration of dose and not of duration of the hormone message. It is admitted that a "physiological" dose provides plasma melatonin levels in the same order of magnitude as a nocturnal peak. Since the regulating system of melatonin secretion is complex, following central and autonomic pathways, there are many pathophysiological situations where melatonin secretion can be disturbed. The resulting alteration could increase the predisposition to disease, add to the severity of symptoms or modify the course and outcome of the disorder. Since melatonin receptors display a very wide distribution in the body, putative therapeutic indications of this compound are multiple. Great advances in this field could be achieved by developing multicentre trials in a large series of patients, in order to establish efficacy of melatonin and absence of long-term toxicity.

Keywords

Circadian rhythms; Glande pinéale; Humain; Human; Melatonin; Mélatonine; Pathophysiology; Physiologie; Physiology; Rythmes circadiens.

Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Articles similar to "Melatonin: Physiological Effects in Humans."

• The properties of Melatonin: Melatonin: Pharmacology, Functions and Therapeutic Benefits. ( Melatonin synchronizes central but also peripheral oscillators (fetal adrenal gland, pancreas, liver, kidney, heart, lung, fat, gut, etc... This review highlights the high number and diversity of major melatonin effects and opens important perspectives for measuring melatonin as a biomarker (biomarker of early identification of certain disorders and also biomarker of their follow-up) and using melatonin with clinical preventive and therapeutic applications in newborns, children and adults based on its physiological regulatory effects. )

Previous article

Inulin: Properties, Health Benefits and Food Applications.

Next article

Melatonin: Pharmacology, Functions and Therapeutic Benefits.