Virus robs addicts of their high
Transgenic carrier inactivates cocaine in rat brains.
A cure for cocaine addiction is one step closer. A method has been developed of mopping up the drug in the brain so that it produces less euphoria. Scientists hope that addicts will be less inclined to keep taking the drug if they do not get their hit.
The idea of inactivating cocaine once it is in the body is not new. One approach is to inject addicts with antibodies that bind to the drug, in an attempt to counteract its powerful effect.
Previously, these antibodies were unable to get into the brain, so the effect of the treatment was limited. The new method uses a virus that invades the brain to deliver the antibodies.
“It’s a neat idea,” comments Arnold Ruoho, a pharmacologist at the University of Wisconsin–Madison. The virus is safe, he says, because any harmful gene sequences have been removed, but genes for the appropriate antibodies have been inserted into the virus’s genome.
The treatment was developed by Kim Janda, a chemist at the Scripps Research Institute in La Jolla, California, and her colleagues. They gave eight rats nasal injections of the virus twice a day for three days and compared them to eight rats that did not receive the treatment. On the fourth day, they gave both groups a dose of cocaine.
The untreated rats behaved in a characteristic way after receiving the drug: sniffing, standing up on their hind legs and rocking backwards and forwards. But the rats that received the virus showed much less severe behaviour.
“If they are not demonstrating this activity, they are probably not feeling the high,” says Janda.
Although human cocaine addicts do experience withdrawal symptoms, the main driving force that pushes recovering addicts into relapse is the psychological desire for a hit, Janda explains.
She hopes that addicts who want to quit could eventually be given the treatment. “It’s for weak moments,” she says. The virus lingers in the brain for around two weeks, so although they might relapse once, the absence of any euphoric feeling would then discourage them from taking it again.
- Carrera R. A., et al. PNAS, published online, doi:10.1073/pnas.04030795101 (2004).