The circadian rhythm plays a key role in the growth of fat cells
In 2017, the Nobel Prize in Medicine was awarded for research into the functioning of the internal clock, which controls the biorhythms of living beings. Knowledge of the circadian rhythm of living beings has shed new light on many biological processes such as metabolism. Two ongoing studies now show that this rhythm also plays a crucial role in weight gain.
In two recent studies, researchers from Weill Cornell Medicine in New York (USA) showed that disruptions of the circadian clock caused by stress play a crucial role in weight gain. The findings were recently published in the journals Proceedings of the National Academies of Sciences (PNAS) and Cell Reports.
What is the circadian rhythm?
The ability of organisms to synchronize physiological processes over a period of approximately 24 hours is called the circadian rhythm. One of the most important circuits in this context is the sleep-wake cycle.
All cells in the body are regulated on a 24-hour day-night cycle. As two ongoing studies show today, disturbances of this rhythm play a decisive role in the growth of fat cells and therefore in weight gain.
Chronic stress makes you fat
The first of the two studies was published in June 2022 in the renowned specialist journal "Cell Reports". Researchers found that chronic stress caused by glucocorticoid stress hormones disrupted the normal circadian cycle in mice and was associated with fat cell growth and increased insulin production.
Disturbances of the internal clock promote the formation of fat cells
In the second study just published, the working group showed that fat cell progenitor cells transform into fat cells during periods of rest. The results suggest that disturbances in the internal clock contribute more to weight gain than previously thought. The results open up new treatment approaches for overweight and obesity.
"There are many forces that act against a healthy metabolism when we are out of circadian rhythm," confirms Professor Dr. Mary Teruel, the lead author of both studies.
Mouse under constant stress
In the first study, scientists administered glucocorticoids to a group of mice for 21 days. Within three weeks, the animals then stored twice as much fat as a comparison group of mice that weren't given any stress hormones. All mice received the same diet throughout the study.
Stress can have dramatic effects on metabolism
“Stressing animals at the wrong time has dramatic effects,” confirms Dr. teruel According to her, mice do not eat differently, but there is always a major change in metabolism that leads to weight gain.
Without stress, metabolism normalized
After the end of the administration of the stress hormones, the metabolism of the animals quickly returned to normal. "This shows that animals can withstand chronic stress for some time," says the scientist.
Metabolic processes understood in detail
In the follow-up study, the researchers were able to track important metabolic processes using fluorescent proteins. This revealed fluctuations in protein release that depended on the circadian rhythm.
During periods of rest, there was a rapid increase in a protein that turns fat cell progenitor cells into fat cells. “The decision to become a fat cell is made within four hours,” says Dr. Teruel. However, according to her, this only happens at a certain time of the day.
Taken together, the findings suggest that the circadian clock regulates the release of proteins that give rise to fat cells, and that stress can upset this natural balance.
Circadian Rhythm Disruption as a Cause of Obesity
The body has protective mechanisms through which stressful conditions can be intercepted over a short period of time. However, a permanent disruption of the circadian rhythm could be the cause of excessive weight gain.
"Each cell in our body has its own cellular clock, just like fat cells, and we have a master clock in our brain that controls hormone secretion," summarizes the author of the study. In further work, the working group now wants to find out how individual cell clocks can be synchronized with the body's master clock. (vb)
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This text corresponds to the specifications of the specialized medical literature, medical guidelines and current studies and has been verified by health professionals.
Graduate editor (FH) Volker Blasek
Sources:Weill Cornell Medicine: Circadian Clocks Play a Key Role in Fat Cell Growth (Published: 08/08/2022), news.weill.cornell.eduZhi-Bo Zhang, Zahra Bahrami-Nejad, Mary N. Teruel, et al . : the circadian clock mediates the daily bursts of cell differentiation by periodically limiting the commitment of cell differentiation; in: PNAS (2022), pnas.orgStefan Tholen Roma PatelMary N Teruel, et al. : Flattening of circadian glucocorticoid oscillations results in acute hyperinsulinemia and adipocyte hypertrophy; in: Cell Reports (2022-9, cell.com
This article contains general advice only and should not be used for self-diagnosis or treatment. It cannot substitute a visit to the doctor.