Dopamine found to be linked with obesity

UPTON, N.Y., Oct. 25 (UPI) -- U.S. scientists have determined dopamine -- a brain chemical associated with reward, pleasure, movement and motivation -- also plays a role in obesity.

Brookhaven National Laboratory researchers made the discovery during a brain-imaging study of genetically obese rats.

The scientists found the obese rats had lower levels of dopamine D2 receptors than did lean rats. They also demonstrated restricting food intake can increase the number of D2 receptors, partially attenuating normal declines associated with aging.

"This research corroborates brain-imaging studies conducted at Brookhaven that found decreased levels of dopamine D2 receptors in obese people compared with normal-weight people," said neuroscientist Panayotis Thanos, lead author of the study.

The researchers, however, didn't determine whether reduced receptor levels are a cause or consequence of obesity. But, either way, the scientists said the study suggests increasing receptor levels by restricting food intake might enhance the impact of the common strategy for combating obesity.

The finding might also help explain why food restriction slows other changes associated with aging, such as declines in locomotor activity and sensitivity to reward.

The research is available in the online edition of the journal Synapse and will appear in an upcoming print issue.