Scientists are experimenting with genetically modified mice.  It unveiled a molecular pathway which is helping us explaining drug addiction and appetite.  There is a chemical process in which the people become substance dependent.  This has been published in nature.  The pleasure giving drugs help boosts the level of dopamine.  It stimulates the brain’s reward center.  It is one part of the molecular cascade that leads to dependence.  At Pierre and Marie Curie University of Paris, Jean Antoine Girault looked at the brain protein called DARPP-32.  It helps the dopamine signaling process. 

Now the experiment was done in the following way…………

The lab mice was given a shot of cocaine, amphetamine and dopamine.  The DARPP-32   is built in part of the brain called straitum.  They created a mice whose DNA had been modified.  The gene expressing DARPP-32 turned into a slightly altered form of protein.  Only one amino acid building block changed.  When the experiment was done on mutant mice and wild mice, it was found that the drug has less effect on the engineered mice.  They observed the movement.  The rats are less likely to crave for another dose.