Researchers at the U.S. Department of Energy's Brookhaven National Laboratory have shown that increasing the brain level of receptors for dopamine, a pleasure-related chemical, can reduce use of cocaine by 75 percent in rats trained to self-administer it. Earlier research by this team had similar findings for alcohol intake. Treatments that increase levels of these chemicals - dopamine D2 receptors -- may prove useful in treating addiction, according to the authors. The study will be published online April 16 and will appear in the July 2008 issue of Synapse.