Mutant mice show new pathway in drug addiction

Researchers led by Jean-Antoine Girault of the Pierre and Marie Curie University in Paris looked at a brain protein called DARPP-32 which helps the dopamine signaling process.

The team found that when lab mice were given a jolt of cocaine, amphetamine or morphine, DARPP-32 built up in part of the brain called the striatum.

They then created mice whose DNA had been modified so that the gene expressing DARPP-32 turned out a slightly altered form of this protein -- a form where just one amino acid building-block had been changed.

Mutant mice and wild mice were given two shots of cocaine or morphine seven days apart. The drugs had far less effect on the engineered mice, as shown in their movement, and these rodents were far less likely to crave another dose.