US scientists have found a key mechanism in the brain that helps explain why cocaine is so addictive and could pave the way towards a potential cure, a study showed Thursday.
Researchers revealed how the highly-addictive drug brings on changes in the brain through a process which influences the expression of genes without changing the brain's gene sequence.
These changes in the brain's pleasure circuits, which are also the first to be influenced by chronic cocaine exposure, appear to promote cravings for cocaine, said the study published in Science.
"This fundamental discovery advances our understanding of how cocaine addiction works," said Nora Volkow, director of the National Institute of Drug Abuse.
"Although more research will be required, these findings have identified a key new player in the molecular cascade triggered by repeated cocaine exposure, and thus a potential novel target for the development of addiction medications."
The research was carried out on mice. One group was given repeated doses of cocaine, the second was given a saline solution with a final dose of the drug to study what differences there were between repeated cocaine exposure and a one-time dose.
Those mice repeatedly given cocaine displayed dramatic alterations in their gene expression as well as a strong preference for the drug.
The study confirmed cocaine appears to block an enzyme that plays a critical role in the so-called "epigenetic" control of gene expression.
The study authors also showed that by reversing the repression of the enzyme, known as G9a, they could inhibit cravings for cocaine.
"The more complete picture that we have today of the genetic and epigenetic processes triggered by chronic cocaine give us a better understanding of the broader principles governing biochemical regulation in the brain," said Eric Nestler, director of the Brain Institute at Mount Sinai School of Medicine.
That could "help us identify not only additional pathways involved but potentially new therapeutic approaches," he added.