Led by Xia Zhang, associate professor in the University of Saskatchewan department of psychiatry, researchers discovered that a naturally occurring enzyme known as PTEN acts on the ventral tegmental area (VTA) of the brain where addictive drugs produce their rewarding effects.
"Our results suggest a potential universal strategy for treating drug addiction," Zhang said. "Most drugs of abuse act on the neurons in this area." But Zhang added that much work remains to be done before a treatment based on the discovery could be developed to help drug addicts, including several years of further testing, including animal and human trials. "We have our peptide, but there's a long way to go before a clinical application."
Blocking the Reward ProcessVTA brain cells are sensitive to serotonin, a hormone associated with learning, sleep and mood, Zhang said in a news release. Working with researches at the University of Toronto and Vanderbilt University, Zhang made the following conclusions:
- The enzyme PTEN acts on the serotonin receptors to increase brain activity in the same way drugs of abuse do to spark the "reward" process.
- The researchers designed a molecule, called a peptide, which fit the serotonin receptors to block PTEN.
- Treating rats with the peptide blocker, researchers shut down the drug reward process, including the brain activity that produces craving and withdrawal.
Source: Zhang's finding were published in the March 2006 issue of the journal Nature Medicine. See also Canadian Institutes of Health Research news release.