Appetite-related chemical also affects drug-seeking: Hungry rats more resistant to drug relapse in absence of chemical signal

These results, which have implications for drug treatments, were presented at Neuroscience 2010, the annual meeting of the Society for Neuroscience, held in San Diego.

More than 2.4 million Americans are in some sort of rehabilitation program for drug use. Yet 40 to 60 percent of drug addicts relapse when trying to get sober, often because of stressful situations. Scientists use animal models of drug use to further understand addict-like behavior and relapse, training rats to press a lever to self-administer heroin or other illicit drugs. Previous studies employed food deprivation as the stress "trigger" for potential relapse in drug-deprived animals. These studies showed that rats exposed to a short period of intense hunger quickly seek out drugs, mimicking the behavior of a relapsed addict.

The new results suggest that a molecule known as NPY, which is released into the body in times of food restriction, also acts as a trigger for drug-seeking. In this study, Concordia University researchers found that rats given a chemical that blocks the NPY brain receptors don't search for heroin. Moreover, the authors observed no side effects from the drugs in the rats, such as weight loss or behavioral changes.

"Our findings suggest a novel approach to the treatment of drug addiction, at least for addicts who also have eating disorders," said Uri Shalev, PhD, the study's lead author.

Research was supported by the Natural Science and Engineering Council of Canada, funds from the Canada Research Chair to the United States, and the Fonds de la recherche en santé du Québec.