A previous study, published in Cell Reports, had shown, in mice, that the stress caused by the chronic administration of glucocorticoid stress hormones and disruption of the circadian cycle triggers a temporary protective mechanism: this mechanism stimulates the growth of fat cells and insulin production while reducing excess blood sugar and fat levels in the blood and liver.
The study shows, once more in mice, that the precursors of fat cells commit to becoming fat cells during the rest period.
Taken together, these data confirm, unsurprisingly, that stress and other factors that disrupt the body’s “clocks” contribute to weight gain and suggest new approaches to treating obesity.
“Living outside the circadian rhythm is a lot of forces once morest a healthy metabolism”,
summarizes lead author Dr. Mary Teruel, associate professor of biochemistry at Weill Cornell Medicine.
- When researchers mimic, in mice, the disruptive effects of diseases like Cushing’s disease or chronic stress on the daily fluctuations of glucocorticoids, a class of stress hormones, the amount of brown and white fat doubles in 21 days and insulin levels soar;
- surprisingly, these metabolic disturbances seem to exert a “protective effect” by keeping blood sugar levels low and preventing fats from accumulating in the blood or liver: this suggests a protective mechanism to make coping with chronic stress for a period of time;
- when scientists optogenetically attach a red fluorescent protein to a protein that controls the expression of important circadian clock genes and a yellow fluorescent protein to a protein-activated receptor gamma that regulates fat cell production, they find that when the circadian protein is disrupted, precursor cells commit to becoming fat cells, within days. In other words, a disruption of the biological clock accelerates the formation of adipose tissue.
“The decision to become a fat cell is made in 4 hours. It’s like a switch
and this process only takes place at a specific time of the day”.
Understand why the disruption of daily rhythms of glucocorticoids triggers temporary protective metabolic changes, this is the next goal of the research team, with immediate implication, determining how long treatment with glucocorticoids remains “safe”.
Finally, this work will contribute to the development of drugs aimed at resetting circadian rhythms in obese people as an alternative to more invasive treatments such as bariatric surgery.
