Impact of Melatonin on Vascular Health in Humans

Abstract

Melatonin, a circadian hormone released from the pineal gland, has recently been recognized to be involved in the pathophysiology of cardiovascular disease. Due to systemic localization of its receptors, melatonin is thought to play an important role in the regulation of vascular function. Data from animal models provide evidence that melatonin is protective against endothelial damage and the subsequent development of atherosclerosis. However, the effects of melatonin on vascular function in humans have yet to be determined.PurposeThe present study tested the hypotheses that, in humans 1) endogenous melatonin production is associated with vascular health and 2) supplemental melatonin improves vascular health.MethodsUpon arrival to the lab, 12 apparently healthy adult men (28±3 y) provided an overnight urine sample to measure 6‐sulfatoxymelatonin, the urine metabolite of melatonin. Subsequently, vascular endothelial function (flow‐mediated dilation; FMD) was assessed. In a follow‐up experiment, a comprehensive assessment of vascular health including brachial arterial blood pressure, FMD, and arterial stiffness (carotid‐femoral pulse wave velocity; PWV) was assessed in 4 individuals (31±6 y) at baseline and 1 hour following a single oral dose of melatonin (5 mg).ResultsFMD (%) was positively associated with total overnight melatonin production (ng; r=0.592, p=0.042) and melatonin excretion rate (ng/hour; r=0.539, p=0.071). Compared with baseline, PWV significantly decreased (5.9±1.3 to 5.7±1.3 m/s, p=0.003) and FMD increased (7.5±2.2 to 8.1±1.8 %, p=0.173) 1 hour following ingestion of supplemental melatonin. Supplemental melatonin did not change blood pressure (114±6 to 114±9 mm Hg, p=0.927).ConclusionThese novel data in humans demonstrate that higher endogenous melatonin production is associated with greater vascular endothelial function. In addition, a single dose of supplemental melatonin is capable of reducing arterial stiffness and improving endothelial function. Together, these findings suggest that melatonin may serve a beneficial role in regulating vascular function in humans. Achieving adequate overnight melatonin production may represent an important therapeutic strategy for the maintenance of optimal vascular health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.