Stomach Nerves Act as Circadian "Food Clock"

Stomach nerves act as circadian clock, limiting food intake to specific times of the day. Disruption to this rhythm may lead to obesity.

Nerves in the stomach act as a circadian clock, limiting food intake to specific times of the day, according to University of Adelaide researchers. The discovery, published in the December issue of The Journal of Neuroscience, could lead to new information about how the gut signals to our brains about when we're full, and when to keep eating.

The researchers at the the University's Nerve-Gut Research Laboratory investigated how the nerves in the stomach respond to stretch, which occurs as a consequence of food intake, at three-hourly intervals across one day.

"These nerves are responsible for letting the brain know how much food we have eaten and when to stop eating," said Dr Stephen Kentish, lead author of the study.

"What we've found is that the nerves in the gut are at their least sensitive at time periods associated with being awake, he said. "This means more food can be consumed before we feel full at times of high activity, when more energy is required."

However, "with a change in the day-night cycle to a period associated with sleeping, the nerves in the stomach become more sensitive to stretch, signaling fullness to the brain quicker and thus limiting food intake. This variation repeats every 24 hours in a circadian manner, with the nerves acting as a clock to coordinate food intake with energy requirements," he added.

So far this discovery has been made in laboratory studies, not in humans.

"Our theory is that the same variations in nerve responses exist in human stomachs, with the gut nerves being less sensitive to fullness during the day and more sensitive at night," Dr Kentish noted.

Study leader Amanda Page, Associate Professor, said this research could lead to further discoveries about how changes in people's circadian clocks affect their eating habits.

"We know that shift workers, for example, are more prone to disruptions in sleep and eating behavior, leading to obesity and other health problems. We are now conducting further research to see what kind of impact such changes to the circadian rhythm will have on eating behavior, and how the nerves in the stomach react to those changes," Ms. Page said.

This study has been funded by the National Health and Medical Research Council (NHMRC) in Australia.

Updated on: November 25, 2015