Diurnal rhythm of circulating nicotinamide phosphoribosyltransferase (Nampt/visfatin/PBEF): Impact of sleep loss and relation to glucose metabolism

Abstract

Context: Animal studies indicate that nicotinamide phosphoribosyltransferase [Nampt/visfatin/pre-B-cell colony-enhancing factor (PBEF)] contributes to the circadian fine-tuning of metabolic turnover. However, it is unknown whether circulating Nampt concentrations, which are elevated in type 2 diabetes and obesity, display a diurnal rhythm in humans. Objective: Our objective was to examine the 24-h profile of serum Nampt in humans under conditions of sleep and sleep deprivation and relate the Nampt pattern to morning postprandial glucose metabolism. Intervention: Fourteen healthy men participated in two 24-h sessions starting at 1800 h, including either regular 8-h-night sleep or continuous wakefulness. Serum Nampt and leptin were measured in 1.5- to 3-h intervals. In the morning, plasma glucose and serum insulin responses to standardized breakfast intake were determined. Main Outcome Measures: Under regular sleep-wake conditions,Nampt levels displayed a pronounced diurnal rhythm, peaking during early afternoon (P<0.001) that was inverse to leptin profiles peaking in the early night.Whensubjects stayed awake, the Nampt rhythm was preserved but phase advanced by about 2 h (P < 0.05). Two-hour postprandial plasma glucose concentrations were elevated after sleep loss (P<0.05), whereas serum insulin was not affected. The relative glucose increase due to sleep loss displayed a positive association with the magnitude of the Nampt phase shift (r=0.54; P<0.05). Conclusions: Serum Nampt concentrations follow a diurnal rhythm, peaking in the afternoon. Sleep loss induces a Nampt rhythm phase shift that is positively related to the impairment of postprandial glucose metabolism due to sleep deprivation, suggesting a regulatory impact of Nampt rhythmicity on glucose homeostasis. Copyright © 2012 by The Endocrine Society.