Thursday, March 27, 2014
Melatonin, an evolutionary ancient molecule that, in mammals, is secreted from the pineal gland, is a hormone that plays a major role as a key regulator of the circadian cycle, along which virtually all metabolic activities are coordinated.
A paper by José Cipolla-Neto and colleagues, published in the Journal of Pineal Research, provides a fascinating overview of how melatonin plays a significant role in energy metabolism.
Its first role relates to insulin secretion and action. Thus, melatonin is not only necessary for the proper synthesis and secretion of insulin, it also plays a role in the insulin-signalling pathway through its effects on GLUT4 receptors.
Secondly, as a powerful chronobiotic, it helps coordinate various metabolic processes so that the activity/feeding phase of the day is associated with higher insulin sensitivity whereas the rest/fasting phase is synchronized to lower insulin sensitivity.
Thirdly, melatonin plays an important role in regulating energy flow to and from fat stores and directly regulating the energy expenditure through the activation of brown adipose tissue and participating in the browning process of white adipose tissue.
The paper discusses how the reduction in melatonin production, as seen during aging, shift-work or night-time light exposure can induce insulin resistance, glucose intolerance, sleep disturbance and metabolic circadian disorganization, which together can lead to weigh gain.
Thus, the available data supports the notion that melatonin replacement therapy may provide a novel strategy to influence metabolism, at least in people with disruptions in their melatonin system.
Clearly, these notions need to be tested in well-controlled randomised trials but there certainly appears to be ample data to suggest that such a trial may well be worthwhile.
If you have taken melatonin or prescribed it to your patients, I’d certainly like to hear about your experience.
Hat tip to Sukie for pointing me to this article.
Cipolla-Neto J, Amaral FG, Afeche SC, Tan DX, & Reiter RJ (2014). Melatonin, Energy Metabolism and Obesity: a Review. Journal of pineal research PMID: 24654916