A diet that is too high in fat could disrupt neuronal activity in an area of the brain associated with circadian rhythms.
- One of the limitations of the study is that the circadian rhythms of rats are reversed from those of humans: they are nocturnal animals.
- Restoring circadian rhythms could prevent over-consumption of calories.
- 17% of adults are obese in France.
The consequences of obesity are visible, but its causes remain poorly understood. In most cases, a combination of factors explains its appearance. In Tea Journal of Physiology, a team of Polish researchers presents a new explanation. According to their results, a diet that is too high in fat could disrupt the circadian rhythm and thus contribute to the onset of obesity. The notion of circadian rhythm designates the biological rhythm: the 24-hour cycles where periods of wakefulness and sleep alternate.
A very high fat diet
In this research, the scientists relied on the observation of rats. They were fed according to two diets: either a balanced diet, in which fats represented 10% of total calories, and either a diet excess in fat, they accounted for 70% of all calories. To mimic the impact of overeating on humans, the researchers fed this new diet to adolescent rats (4 weeks old) and monitored them for four weeks.
Effects on neurons
To understand the effect of diet on the circadian rhythm, researchers looked at the dorsal vagal complex, part of the brainstem. Previous studies have shown that this set has a role in controlling food intake. In this research, electro-physiological recordings were made to measure the evolution of neuronal activity in the dorsal vagal complex. The use of electrode arrays made it possible to simultaneously monitor around 100 neurons from each slice of the brainstem. Thus, the researchers were able to assess circadian changes in neuronal activity as well as neuronal responses to hormones related to each of the diet groups. They found disturbances in the circadian rhythm of rodents. In those fed a high-fat diet, the peak of activity in the dorsal vagal complex was at the end of the day, when it is normally a resting phase.
Restore the biological clock to fight against obesity?
For the authors of this study, the results are promising for the fight against obesity. “I’m really excited about this research because of the possibilities it offers to fight obesitypoints out Dr. Lukasz Chrobok, lead author of the research. We still don’t know what temporal cues can reset or synchronize the brainstem clock.” He hopes that the restoration of circadian rhythms will lead to the development of new therapeutic avenues.
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