Dopamine Receptors Implicated in Obesity

By HospiMedica staff writers
Posted on 06 Feb 2001

Researchers have discovered that a deficiency of dopamine in the brain may explain why some individuals engage in pathological overeating. The study was sponsored by the U.S. National Institute on Drug Abuse, and the findings were published in the February issue of The Lancet.

In the study, involving 10 severely obese individuals and 10 controls, dopamine receptors in the brain were measured with positron emission tomography (PET) scans and other tests. These showed that dopamine receptors values were significantly lower in obese subjects than in the controls. An additional finding was that body mass index correlated negatively with the measures of dopamine receptors. Subjects with the lowest dopamine receptor values had the largest body mass index.

Dopamine helps regulate feelings of pleasure and modulates the rewarding properties of food. The researchers believe that individuals deficient in dopamine receptors may need to eat more than people with higher dopamine levels to induce feelings of satisfaction and gratification. A reduction in dopamine receptors has also been noted in individuals addicted to various types of drugs including cocaine, alcohol, and opiates. Thus, dopamine deficiency may be associated with addictive behavior whether related to food or to drugs.

Previous studies have found that certain antipsychotic medications result in weight gain, while drugs such as methamphetamine that increase dopamine levels diminish appetite. This suggests that improving dopamine receptor function might lead to a better treatment for obesity.

"Currently, the most appropriate practical application of this finding is to urge overweight individuals to exercise,” noted Dr. Gene-Jack Wang, of Brookhaven National Laboratory, who headed the team of researchers. "In laboratory animals, exercise has been shown to increase dopamine release and to increase the number of dopamine receptors, which would help quell the urge to pathologically overeat.”

Related Links:
The Lancet
National Institute on Drug Abuse