Drug Abuse and Obesity Share Brain Mechanism

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A study by the Scripps Research Institute has confirmed the notion that the brain’s reward system and dopamine are tied to both drug addiction and compulsive eating.

Three groups of rats were observed for 40 days, with each having full access to standard chow. Two of the groups also had access to a cafeteria diet, or foods high in fat, such as pound cake and bacon, for short or long periods of time. After 40 days, the rats were not given any more of the high-fat foods.

Researchers measured caloric intake, weight gain and brain reward circuits for reward thresholds – or the amount of food needed to satisfy desires to eat – of the rats.

While all the rats gained weight, those with extended access to high-fat foods gained more weight compared to others. The researchers found that for two weeks after access to the cafeteria foods was denied, the brain reward thresholds in the rats continued to rise, resulting in compulsive eating habits.

This was explained by the decrease in the rates of type 2 dopamine receptors (D2R), which are related to drug addiction. The less D2R in the rats, the stronger their eating habits became.

The researchers expressed hope that the information ultimately will lead to drugs to combat both addiction and obesity.

Free. Available only on website. http://www.nih.gov/researchmatters/april2010/04122010compulsive.htm.