New insights into the function of melatonin and its role in metabolic disturbances

ABSTRACT

Introduction: Melatonin is a pineal hormone that has acquired several unique modes of regulating the physiological effects in mammals due to its characteristic phylogenetic history. While melatonin exhibits immediate nocturnal effects, it also has next-day prospective effects that take place in the absence of this hormone. Besides that, the daily repetition and the annual variation in the duration of its synthesis determine its circadian and seasonal effects that characterize melatonin as a chronobiotic, a molecule that encodes time to the internal environment. Additionally, it presents transgenerational effects that are important for fetal programming, leading to a balanced energy metabolism in the adult life.

Areas covered: Physiology, pathophysiology and therapeutic value of melatonin in metabolism and metabolic disorders.

Expert opinion: The typical mechanisms of action of melatonin (immediate, prospective, chronobiotic and transgenerational) should be considered to adequately understand its physiological effects on the regulation of metabolism in humans and, as a result, to understand the metabolic pathophysiological consequences caused by its synthesis and/or signaling disturbances. That points to the importance of a broader understanding of melatonin actions, besides the classical endocrinological point of view, that would allow the clinician/research to proper interpret its role in health maintenance.

KEYWORDS:

• Body Weight
• energy metabolism
• glucose homeostasis
• insulin resistance
• melatonin
• melatonin therapy

Article highlights

• Melatonin: basic aspects, mechanisms and modes of action

• Melatonin exhibits immediate effects which occur during the night and primes next-day effects that will take place in the absence of circulating melatonin

• Melatonin regulates glucose metabolism by inducing nocturnal insulin resistance and diurnal insulin sensitivity, which is closely associated with nocturnal fasting and diurnal feeding

• Melatonin regulates energy homeostasis, influencing feeding, and energy storage and expenditure

• Melatonin tips the energy balance in the direction of reducing food intake and increasing brown adipose tissue energy expenditure, preventing excessive body weight gain

• The regular use of melatonin for therapeutic purposes should always be taken at night and the dose and formulation should be personalized in order to prevent the lingering effects of melatonin blood pharmacological profile the next morning.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was funded by FAPESP – São Paulo Research Foundation Grant 2014/50457-0.