Gut-brain communication failure can trigger overeating

Posted Aug 23, 2013 by Tim Sandle
Repairing a faulty communication line between the gut and the brain could suppress the urge to overeat. This is the outcome of a study on mice and scientists think that a similar strategy could be used to treat compulsive eating in people.
Some scientists have argued that overeating resembles a form of drug addiction, in that the more food a person consumes, the less responsive the brain becomes to the pleasure of eating. The argument then follows, the Boston Globe reports, that by restoring normal communication between the gut and brain, the compulsion to overeat diminishes.
In the brain, it has been observed that a chemical called dopamine surges in response to pleasurable experiences like eating. Moreover, brain-scanning studies suggest that obese individuals have muted dopamine responses to food.
To explore this theory, scientists undertook some experiments using mice. Through animal studies researchers were able to 're-sensitize' overfed rodents to the pleasures of both fatty and healthy foods.
To start with, U.S. News reports, the science group found that mice get a dopamine rush when fat is introduced directly into the small intestine via catheters. This shows that the gut communicates with the brain’s reward center even when the mouse cannot actually taste the food. As part of the next phase, the group found that mice fed a high-fat diet for 15 weeks do not experience the normal dopamine surge after an infusion of gut calories.
The team then found that the disruption in dopamine levels involved a molecule called oleoylethanolamine, which is thought to suppress appetite. In normal mice, eating boosts levels of the molecule in the small intestine and this increase is thought to help animals stop feeding when they are full. However, the rodentsfed a high-fat diet have abnormally low levels of oleoylethanolamine.
In the final part of the study, the researchers gave the overfed mice injections of oleoylethanolamine and found that, instead of dopamine levels dropping when fat infusions hit the intestines, the mice experienced a dopamine surge. This caused the animals to eat less and they lost weight.
For future research, the scientists aim to see whether oleoylethanolamine, or a drug that mimics its effects, could treat obesity in people. The research findings to date have been published in the journal Science.