Summary: A new study from the Perelman School of Medicine at the University of Pennsylvania has discovered that the liver communicates with the brain via the vagus nerve to regulate eating patterns based on the body’s circadian rhythm. This internal clock helps signal when the body should consume food, but disruptions—such as working night shifts or irregular hours—can interfere with these signals, potentially leading to overeating and increased risk of weight gain and diabetes. By targeting specific genes in mice, researchers found that altering the liver-brain pathway could reset disrupted eating patterns, opening up new possibilities for managing metabolic disorders in individuals with irregular schedules.
Key Takeaways:
- Liver-Brain Communication Influences Eating Habits: The study found that the liver sends signals to the brain to regulate meal timing, aligning eating patterns with the body’s natural circadian rhythm.
- Targeting Nerve Pathways Could Reduce Overeating: Researchers discovered that cutting the nerve connection in obese mice restored normal eating habits, suggesting a potential therapy for metabolic disorders caused by irregular schedules.
- Implications for Shift Workers and Jet Lag: Findings highlight the possibility of developing therapies to help those with disrupted circadian rhythms, such as night shift workers, manage weight gain and related health issues.
People who work the night shift or odd hours and eat at irregular times are more prone to weight gain and diabetes, likely due to eating patterns not timed with natural daylight and when people typically eat.
But is it possible to stave off the ill effects of eating at these “unusual” times despite it not being biologically preferable? A new study from the Perelman School of Medicine at the University of Pennsylvania says yes and sheds light on how the body knows when to eat. The study, published in Science, explains how researchers discovered a connection between the liver’s internal clock and feeding centers in the brain.
Liver-Brain Communication
The team’s research showed that the liver sends signals to the brain via the vagus nerve, letting the brain know if eating is happening at a time that follows the body’s circadian rhythm. These signals can get disrupted from working unusual hours. The brain then overcompensates, leading to overeating at the wrong times.
“Both mice and humans normally eat at times when they are awake and alert, and this circuit provides feedback from the liver to the central clock in the brain that keeps the system running smoothly,” says the study’s senior author, Mitchell Lazar, MD, PhD, the director of Penn Medicine’s Institute for Diabetes, Obesity, and Metabolism, and the Ware Professor of Diabetes and Metabolic Diseases, in a release. “This feedback is through a nerve connection from the liver to the brain”.
A Promising Approach for Weight Management
Researchers specifically targeted genes called REV-ERBs in the liver cells of mice. REV-ERBs are important proteins that help regulate the body’s circadian rhythm. The body’s circadian rhythm is an internal 24-hour cycle that regulates various activities including sleep-wake cycles, hormone release, and eating habits. When these REV-ERB genes were turned off in mice—making the liver have a faulty clock—eating patterns shifted dramatically, with more food consumed during less active times.
The effects were reversible. Cutting the nerve connection in obese mice restored normal eating patterns and reduced food intake.
“This suggests that targeting this liver-brain communication pathway could be a promising approach for weight management in individuals with disrupted circadian rhythms,” says Lauren N. Woodie, PhD, a post-doctoral researcher in Lazar’s lab, in a release.
The research team suggests that targeting specific parts of the vagus nerve could help people who work night shifts or experience jet lag by addressing overeating caused by disrupted body clocks.
“These findings open the door to future therapies that can target specific neural pathways to help those struggling with metabolic disorders caused by irregular eating schedules. Future research should focus on what kind of chemical signals the liver sends to the vagus nerve to help us understand how the liver affects the brain and the body through this communication,” the researchers conclude.
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