PNNL

Abstract

The circadian system coordinates daily rhythms in lipid metabolism, storage and utilization. Disruptions of internal circadian rhythms due to altered sleep/wake schedules, such as in night-shift work, have been implicated in increased risk of cardiovascular disease and metabolic disorders. To determine the impact of a night-shift schedule on the human blood plasma lipidome, an in-laboratory simulated shift work study was conducted with 14 healthy young adults. Participants were assigned to 3 days of either a simulated day or night-shift schedule, followed by a 24-h constant routine protocol with fixed environmental conditions, hourly isocaloric snacks, and constant wakefulness to investigate endogenous circadian rhythms. Using untargeted lipidomics analysis of blood plasma collected at 3-h intervals, over 400 lipids were identified and quantified across 21 subclasses. Focusing on lipids with low between-subject variation per shift condition, alterations in the circulating plasma lipidome revealed generally increased mean triglycerides (TGs) levels and decreased mean phospholipids levels after night-shift relative to day-shift. The circadian rhythms of TGs that contained C20, C22, and C24 acyl chains peaked later and TGs that contains odd chain (mostly C15 and C17) fatty acids peaked earlier during constant routine after night-shift. Regardless of shift condition, TGs tended to either peak or be depleted at 16:30 h, with chain specific differences associated with the direction of change. The altered lipidome associated with the simulated night-shift schedule is consistent with the increased cardiovascular risk associated with night-shift work.