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Researchers at the U.S. government's Brookhaven National Laboratory in Upton, N.Y., found that genetically obese rats have lower levels of dopamine D2 receptors on brain cells than lean rats. The study also found that restricting food intake can increase the number of D2 receptors on those cells.
"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," lead author and Brookhaven neuroscientist Panayotis (Peter) Thanos, said in a prepared statement.
"This study also provides further evidence for the interplay of genetic factors with the environment in the development of obesity in our society," he added.
It's not clear whether reduced dopamine D2 receptor levels are a cause or consequence of obesity, Thanos said. Overeating may cause a chronic reduction in receptor levels and, over the long term, contribute to obesity. However, genetically influenced low levels of D2 receptors may also cause obesity, because a person may overeat in an attempt to stimulate a "blunted" reward system.
In both cases, increasing dopamine D2 receptor levels by restricting food intake may prove an effective way of combating obesity, Thanos said.
"Consuming fewer calories is obviously important for people trying to lose weight, plus improving the brain's ability to respond to rewards other than food may help prevent overeating," Thanos noted.
The findings are available online and are expected to be published in an upcoming print issue of the journal Synapse.
-- Robert Preidt
SOURCE: Brookhaven National Laboratory, news release, Oct. 25, 2007
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