Anorexia and ecstasy use activate some of the same brain pathways, according to researchers who used mice to arrive at their conclusions. The findings hint that the condition works in a similar way to drug addiction, and may also point the way towards new drug treatments for the eating disorder.

Those diagnosed with anorexia nervosa restrict their food intake even though they may be in desperate need of energy. The condition has one of the highest mortality rates for any mental disorder, and there are few effective treatments currently available.

Valerie Compan at Centre National de la Recherche Scientifique (CNRS), Montpellier, France, is one of a growing number of researchers who believes that anorexia works in a similar way to addiction and that sufferers become “hooked” on the self-control involved.

After noticing that ecstasy (also called MDMA) use induces appetite suppression, she decided to investigate possible similarities further. Compan and colleagues focused on the nucleus accumbens, a reward centre in the brain with a high density of serotonin receptors – known as 5-HT4 receptors – that are known to play a role in addictive behaviour.


Addictive starving

The team stimulated these receptors in mice and found that this curtailed their urge to eat. The same stimulation also caused the release of a peptide known as CART. Elevated levels of CART have previously been detected following use of psychostimulant drugs, and at least one research group has found it in elevated levels among women suffering from anorexia.

In further experiments, Compan and her team injected mice with CART and also blocked it using RNA interference. Elevated levels of CART caused the animals to eat less and, conversely, lower levels increased their appetites.

Finally, to see if ecstasy-induced appetite suppression is mediated in the same way, the researchers gave the drug to mice engineered to lack 5-HT4 receptors. Unlike normal mice, these modified animals did not lose their appetites, suggesting the receptors do indeed control ecstasy’s appetite-suppressing effect.

Compan says that ecstasy and anorexia may have more in common than we think. Her study suggests that starving yourself can be addictive, and is further evidence that anorexia may be related to neurological defects.

The findings may also highlight targets for drug treatment. “Our studies over seven years open the possibility that the 5-HT4 receptor would represent an important therapeutic target to treat patients suffering from these disorders,” Compan says.

Journal reference: Proceedings of the National Academy of Science (DOI: 10.1073pnas.0701471104)

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