Gene therapy may cut cocaine addiction

Washington, Apr 17 : A new study on mice from US Department of Energy's Brookhaven National Laboratory has shown that boosting the brain level of receptors for dopamine, a pleasure-related chemical, could reduce cocaine use.

Previous studies at Brookhaven Lab have found that chronic abuse of alcohol and other addictive drugs increases the brain's production of dopamine, for the present study scientists hypothesized the same.

"By increasing dopamine D2 receptor levels, we saw a dramatic drop in these rats' interest in cocaine," said Panayotis (Peter) Thanos, lead author and a neuroscientist with Brookhaven Lab and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) Laboratory of Neuroimaging.

"This provides new evidence that low levels of dopamine D2 receptors may play an important role in not just alcoholism but in cocaine abuse as well. It also shows a potential direction for addiction therapies," he added.

The current study suggests that cocaine-dependent individuals may have their need for cocaine decreased if their D2 levels are boosted.

The researchers injected a virus that had been rendered harmless and altered to carry the D2 receptor gene directly into the brains of experimental rats that were trained to self-administer cocaine.

The virus acted as a mechanism to deliver the gene to the nucleus accumbens, the brain's pleasure centre, enabling the cells in this brain region to make receptor proteins themselves. Scientists examined how the injected genes affected the rats' cocaine-using behaviour after they had been taking cocaine for two weeks

The findings revealed that D2 receptor treatment lowered self-administration of the drug by 75 percent.

"This adds another piece to the puzzle of the complex role of dopamine D2 receptors in addiction," said Thanos.

The study is published online April 16 and will appear in the July 2008 issue of Synapse.

ANI