Study Examines Addictiveness of Cocaine

It is a well-known fact that cocaine is highly addictive, but understanding exactly what causes this addiction could help in the development of effective treatments in the future. A recent Science Daily post highlighted that researchers have identified a key epigenetic mechanism in the brain that could help explain the addictiveness of cocaine.

The research was funded by the National Institute on Drug Abuse (NIDA) and published in the January issue of Science. It shows how cocaine affects an epigenetic process – or a process capable of influencing gene expression without changing a gene’s sequence – called histone methylation.

It is believed that these epigenetic changes in the brain’s pleasure circuits, which are first impacted by chronic cocaine exposure, are likely to contribute to an acquired preference for cocaine.

“This fundamental discovery advances our understanding of how cocaine addiction works,” said NIDA Director Dr. Nora D. Volkow, in Science Daily. “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.”

In testing done on young mice, it was discovered that animals exposed to chronic cocaine displayed dramatic alterations in gene expression as well as a strong preference for cocaine. By experimentally reversing the cocaine induced repression of G9A – an enzyme that plays a critical role in epigenetic control of gene expression – they could block the changes in gene expression and inhibit the enhanced preference 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 which will help us identify not only additional pathways involved but potentially new therapeutic approaches,” said Dr. Eric J. Nestler, study investigator and director of the Brain Institute at Mount Sinai School of Medicine.