A recent study found that junk food alters neurological pathways in the brain, reducing its ability to regulate calorie intake. According to the researchers, the mechanism of action of fatty foods on neuronal activity might not only lead to overeating, but also obesity.
A new study published in the journal Journal of Physiology found that junk food reduces the brain’s ability to regulate calorie intake. It would alter neurological pathways, and subsequently disrupt long-term appetite, which might lead to overeating and weight gain.
To reach this conclusion, researchers at the Penn State College of Medicine, in the United States, subjected rats to a diet high in fat and calories for fourteen days. They noted that astrocytes, which are cells responsible, among other things, for regulating short-term caloric intake, become desensitized when fat consumption is continuous.
These star-shaped cells act as intermediaries between the brain and the stomach and provide the nutrients needed to enable neuronal activity in the brain. During the first four days of the study, no abnormalities were observed in the brain and stomach.
Decline in activity following 14 days
After fourteen days, the researchers discovered a drop in astrocyte activity in the rats, which disrupted digestion and appetite.
“Calorie intake appears to be regulated in the short term by astrocytes. We found that brief exposure (three to five days) to a high-fat, high-calorie diet has the greatest effect on astrocytes, triggering the pathway normal signaling to control the stomach.
Over time, astrocytes seem to become desensitized to high fat foods. About 10 to 14 days of a high-fat, high-calorie diet, astrocytes seem unresponsive and the brain’s ability to regulate calorie intake seems to be lost.
This disrupts the signaling to the stomach and delays the way it empties,” says lead author Dr. Kirsteen Browning in the study. A press release.
Normally, the brain has the ability to adapt to react to what is ingested, and reduce the amount of food consumed to balance calorie intake.
Astrocytes initially react when foods high in fat and calories are ingested. Their activation triggers the release of gliotransmitters, chemicals (including glutamate and ATP) that excite nerve cells and activate normal signaling pathways to stimulate neurons that control stomach function.
The release of gliotransmitters allows the contraction of the stomach to fill and empty following food has passed through the digestive system. Over the long term, the chemical signaling cells weaken and make digestion slower: the stomach no longer fills and empties properly.
According to by Dr Kirsteen Browning, it is still unclear whether the decline in astrocyte activity is the cause or the result of the overeating. “We are eager to find out if it is possible to reactivate the brain’s apparent lost ability to regulate calorie intake.
If so, this might lead to interventions to help restore caloric regulation in humans,” she adds. claims the discovery of disruption of a pathway between the brain and stomach might pave the way for an anti-obesity pill that targets brain neurons.
According to a study published in the journal BMJ Global Health in September 2022, nearly two-thirds of adults worldwide are overweight or obese. By 2060, researchers estimate that three out of four adults will be affected. At the end of the study conducted on rats, the American researchers plan to further explore the action of fatty foods on the brain.
Human experiments will need to be conducted to confirm whether the same mechanism occurs in humans. If so, further testing will be needed to assess whether the mechanism can be safely targeted without disrupting other neural pathways.
