Glucose tolerance in mice exposed to light\u2013dark stimulus patterns mirroring dayshift and rotating shift schedules

Mariana G Figueiro,Barbara Plitnick,Mark S Rea,Leora Radetsky

doi:10.1038/srep40661

Mariana G Figueiro, Barbara Plitnick + Show 2 more

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https://doi.org/10.1038/srep40661

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Journal: Scientific Reports	Publication Date: Jan 12, 2017
Citations: 27	License type: open-access

Affiliation: Rensselaer Polytechnic Institute

Abstract

Glucose tolerance was measured in (nocturnal) mice exposed to light–dark stimulus patterns simulating those that (diurnal) humans would experience while working dayshift (DSS) and 2 rotating night shift patterns (1 rotating night shift per week [RSS1] and 3 rotating night shifts per week [RSS3]). Oral glucose tolerance tests were administered at the same time and light phase during the third week of each experimental session. In contrast to the RSS1 and RSS3 conditions, glucose levels reduced more quickly for the DSS condition. Glucose area-under-the-curve measured for the DSS condition was also significantly less than that for the RSS1 and RSS3 conditions. Circadian disruption for the 3 light–dark patterns was quantified using phasor magnitude based on the 24-h light–dark patterns and their associated activity–rest patterns. Circadian disruption for mice in the DSS condition was significantly less than that for the RSS1 and RSS3 conditions. This study extends previous studies showing that even 1 night of shift work decreases glucose tolerance and that circadian disruption is linked to glucose tolerance in mice.

Highlights

Glucose tolerance was measured in mice exposed to light–dark stimulus patterns simulating those that humans would experience while working dayshift (DSS) and 2 rotating night shift patterns (1 rotating night shift per week [rotating shift conditions were comprised of 1 (RSS1)] and 3 rotating night shifts per week [RSS3])
Electrical signals emanating from retinal neurons are carried over the retinohypothalamic tract (RHT) to the master biological clock in the suprachiasmatic nuclei (SCN), which plays a key role in the timing of biological systems ranging from mitotic cell division[3] to endocrine synthesis[4] to behavioral sleep[5]
The present study investigated how circadian disruption measured over the course of 3 consecutive weeks affected glucose tolerance in nocturnal mice

Summary

Introduction

Glucose tolerance was measured in (nocturnal) mice exposed to light–dark stimulus patterns simulating those that (diurnal) humans would experience while working dayshift (DSS) and 2 rotating night shift patterns (1 rotating night shift per week [RSS1] and 3 rotating night shifts per week [RSS3]). The term “circadian disruption” has been coined to encompass a wide range of acute and chronic decrements in performance, sleep, wellbeing, and health that are associated with irregular exposures to light and dark[6,7,8,9,10,11,12,13] It is more practical and less expensive to use animal models rather than humans to perform parametric studies of light-induced circadian disruption and its possible effects on health outcomes. This analysis yields a vector called a phasor, which quantifies how well these patterns are synchronized over a 24-h period (i.e. phasor magnitude) and their stimulus–response phase relationship (i.e. phasor angle) It is perhaps worth emphasizing a key insight gained from the development of phasor analysis—namely, that measurements of light exposures per se, even species-specific light–dark exposures, are not helpful for understanding circadian entrainment and disruption. Previous research has shown that light–dark www.nature.com/scientificreports/

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