Circadian misalignment alters insulin sensitivity during the light phase and shifts glucose tolerance rhythms in female mice

PLoS One. 2019 Dec 18;14(12):e0225813. doi: 10.1371/journal.pone.0225813. eCollection 2019.

Abstract

Shift work and jet lag, characterized by circadian misalignment, can disrupt several physiological activities, but whether they affect the rhythm of glucose uptake and insulin sensitivity remain unclear. In the present study, female C57BL/6J mice were maintained for four weeks under the condition of 8-hour phase advance and delay every 3-4 days to mimic shift work. Intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test (IPITT) were performed repeatedly at Zeitgeber time (ZT) 0, ZT6, ZT12, and ZT18. Glucose-stimulated insulin secretion (GSIS) test was performed at ZT6. We found that the average level of daily glucose tolerance did not decrease but the phase of glucose tolerance advanced by 2.27 hours and the amplitude attenuated by 20.4% in shift work mice. At ZT6, IPITT showed blood glucose at 30 min after insulin injection decreased faster in shift work mice (-3.50±0.74mmol/L, -61.58±7.89%) than that in control mice (-2.11±1.10mmol/L, -33.72±17.24%), but IPGTT and GSIS test showed no significant difference between the two groups. Food intake monitor showed that the feeding time of shift work mice continued to advance. Restricting feed to a fixed 12-hour period alleviated the increase of insulin sensitivity induced by shift-work. We also observed that an increase of blood glucose and liver glycogen at ZT0, as well as a phase advance of liver clock genes and some glucose metabolism-related genes such as forkhead box O1 (Foxo1) and peroxisome proliferator activated receptor alpha (Pparα) in shift work mice. Our results showed that light change-simulated shift work altered insulin sensitivity during the light phase and shifted glucose tolerance rhythms in female mice, suggesting a causal association between long-term shift work and type 2 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose / metabolism*
  • Circadian Rhythm / physiology*
  • Feeding Behavior / physiology*
  • Female
  • Glucose Tolerance Test / methods
  • Insulin / blood*
  • Insulin Resistance / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Shift Work Schedule / psychology*

Substances

  • Blood Glucose
  • Insulin

Grants and funding

This work was sponsored by National Key R&D Program of China (2018YFA0800404 to BZ), the National Natural Science Foundation of China (81773403 to BZ, 81741101 to WZ), Science and Technology Planning Project of Guangzhou City (201707010037 to BZ), Open Project of Guangdong Key Laboratory of Liver Disease Research (GS2017101008 to BZ) and Open Project of Guangdong Provincial Key Laboratory of Tropical Disease Research (to BZ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.