Circadian clock could be influenced by the liver

Liver cells influence the body’s internal circadian clock, which was previously believed to be solely controlled by the brain, according to research led by the University of Queensland.

Associate Professor Frédéric Gachon from UQ’s Institute for Molecular Bioscience and Dr Serge Luquet from Université Paris Cité/CNRS in France and their collaborators have demonstrated that mice with transplanted human liver cells had modified circadian rhythms.

In research published in Science Advances, Gachon said the circadian internal body clock controls most biological functions including sleep, hormone secretion, body temperature and metabolism.

“Mice are nocturnal but when their liver cells were replaced with human cells, their circadian clock advanced by two hours — they ate and slept at different times to mice without those transplanted cells,” Gachon said.

“The mice in our study started to eat and be active before night-time began, which is very unusual for a nocturnal animal.”

Until now, the synchronisation of the mammalian circadian rhythm was thought to be controlled exclusively by a central circadian clock composed of a group of brain cells called the suprachiasmatic nucleus.

Gachon said this study shows human liver cells in a mouse can act on the central clock and modify circadian behaviour.

“Liver disease and metabolic diseases such as diabetes and obesity are associated with disrupted sleep, irregular eating and a disturbance of the circadian clock,” Gachon said.

“This study suggests that the abnormal liver function is likely driving this disturbed rhythm.

“Our study deepens our understanding of the hormonal and neuronal mechanisms involved in the role of the liver in controlling circadian rhythms.

“It suggests that restoring liver physiology could benefit the health and wellbeing of patients.

“It also shows that the regulation of circadian rhythms is more complex than we suspected and presents avenues for investigating potential new treatments for metabolic diseases.”

Image credit: iStock.com/Alexey Yaremenko