Chronic Circadian Disruption Alters Behaviour, Cardiac Function and Glucose Regulation in Mice

The circadian system regulates many physiological functions including the cardiovascular system, metabolism, and stress response. Accordingly, circadian misalignment in mammals contributes to cardiometabolic disease and stress-induced emotional disorders. The BTBR mouse strain shows several abnormalities, including insulin resistance, enlarged hearts, short circadian periods (22.75 hrs), and high stress reactivity. Whether these traits relate to circadian misalignment is less known. Here, we examined how the mismatch between BTBRs’ free-running period and the external light/dark (LD) cycle contributes to their phenotype. We compared cardiometabolic function in BTBR and C57BL/6 (B6) mice conceived and raised in either a 12:12 or 11.375:11.375 LD cycle. We hypothesized that mismatched LD cycles worsen cardiometabolic and behavioural health outcomes. We performed three electrocardiograms in the first 4 months, and a glucose or insulin tolerance test and several behavioural assays at 13 weeks. We found that mice raised in mismatched LD cycles had worse health outcomes, including heightened blood glucose after glucose or insulin bolus, altered cardiac electrophysiology, increased cardiomyocyte size, and an increase in anxiety-like behaviours. Circadian disruption from social/work schedules or disorders in people is often confounded with other unhealthy habits. The present study demonstrates that circadian disruption on its own can lead to adverse health states.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Psychology

Grantor

Arts

Year dc:date.issued

2025

Author dc:creator

• Gearey, Jenna Elizabeth Jeanne

Advisor dc:contributor.advisor

• Antle, Michael

Committee members dc:contributor.committeemember

• Dyck, Richard
• Campbell, Tavis

• Circadian rhythm
• Circadian misalignment
• Cardiac function
• Metabolism
• Anxiety

Statement dc:rights

• Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

https://dx.doi.org/10.11575/PRISM/48841

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/121251