Common Signals May Underlie Obesity and Drug Addiction
Overeating may elicit addiction-like responses in brain reward circuits and drive compulsive eating
MONDAY, March 29 (HealthDay News) -- Over-consumption of calorie-rich food may trigger a reaction similar to cocaine and heroin addiction-like responses, according to a study in rats published online March 28 in Nature Neuroscience.
Paul M. Johnson and Paul J. Kenny, Ph.D., of the Scripps Research Institute in Jupiter, Fla., conducted a study of rats that were offered a range of high-calorie foods such as bacon, cake and chocolate, as well as regular chow. Not only did the rats over-consume the calorie-dense foods and rapidly gain weight, their sensitivity to reward plummeted, similar to the blunting of reward response associated with addictive drugs.
The researchers found that only obese rats developed compulsive-like feeding behavior. Lean rats did not continue to eat when they had been trained to anticipate a painful electric shock, but the obese rats did. In addition, when the high-calorie diet was withdrawn, the obese rats refused to eat. The obese rats had significantly lower levels of dopamine D2 receptors, a phenomenon similar to that which has been found in human drug addicts.
"These findings confirm what we and many others have suspected, that over-consumption of highly pleasurable food triggers addiction-like neuroadaptive responses in brain reward circuitries, driving the development of compulsive eating," Kenny said in a statement. "Common mechanisms may therefore underlie obesity and drug addiction."