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World J Diabetes. Jun 15, 2011; 2(6): 82-91
Published online Jun 15, 2011. doi: 10.4239/wjd.v2.i6.82
Role of melatonin on diabetes-related metabolic disorders
Javier Espino, José A Pariente, Ana B Rodríguez
Javier Espino, José A Pariente, Ana B Rodríguez, Department of Physiology, Neuroimmunophysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, Badajoz 06006, Spain
Author contributions: Espino J wrote the manuscript; Pariente JA and Rodríguez AB revised the manuscript critically for important intellectual content; and all authors approve the final version to be published.
Supported by Ministry of Education (AP2009-0753, to Dr. Javier Espino)
Correspondence to: Javier Espino, MSc, Department of Physiology, Neuroimmunophysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, 06006 Badajoz, Spain. jespino@unex.es
Telephone: +34-924-289388 Fax: +34-924-289388
Received: February 14, 2011
Revised: May 20, 2011
Accepted: May 27, 2011
Published online: June 15, 2011
Abstract

Melatonin is a circulating hormone that is mainly released from the pineal gland. It is best known as a regulator of seasonal and circadian rhythms, its levels being high during the night and low during the day. Interestingly, insulin levels are also adapted to day/night changes through melatonin-dependent synchronization. This regulation may be explained by the inhibiting action of melatonin on insulin release, which is transmitted through both the pertussis-toxin-sensitive membrane receptors MT1 and MT2 and the second messengers 3’,5’-cyclic adenosine monophosphate, 3’,5’-cyclic guanosine monophosphate and inositol 1,4,5-trisphosphate. Melatonin may influence diabetes and associated metabolic disturbances not only by regulating insulin secretion, but also by providing protection against reactive oxygen species, since pancreatic β-cells are very susceptible to oxidative stress because they possess only low-antioxidative capacity. On the other hand, in several genetic association studies, single nucleotide polymorphysms of the human MT2 receptor have been described as being causally linked to an elevated risk of developing type 2 diabetes. This suggests that these individuals may be more sensitive to the actions of melatonin, thereby leading to impaired insulin secretion. Therefore, blocking the melatonin-induced inhibition of insulin secretion may be a novel therapeutic avenue for type 2 diabetes.

Keywords: Melatonin; Circadian rhythm; Diabetes; Insulin secretion; Pancreatic β-cell; Melatonin receptor