It’s hardly a secret that taking cocaine can change the way you feel and the way you behave. Now, a study published in the Jan. 8 issue of Science shows how it also alters the way the genes in your brain operate. Understanding this process could eventually lead to new treatments for the 1.4 million Americans with cocaine problems, and millions more around the world.
The study, which was conducted on mice, is part of a hot new area of research called epigenetics, which explores how experiences and environmental exposures affect genes. “This is a major step in understanding the development of cocaine addiction and a first step toward generating ideas for how we might use epigenetic regulation to modulate the development of addiction,” says Peter Kalivas, professor of neuroscience at the Medical University of South Carolina, who was not associated with the study. Though we think about our genes mostly in terms of the traits we pass on to our children, they are actually very active in our lives every day, regulating how various cells in our bodies behave. In the brain this can be especially powerful. Any significant experience triggers changes in brain genes that produce proteins — those necessary to help memories form, for example. But, says the study’s lead author, Ian Maze, a doctoral student at Mount Sinai School of Medicine, “when you give an animal a single dose of cocaine, you start to have genes aberrantly turn on and off in a strange pattern that we are still trying to figure out.”
Maze’s research focused on a particular protein called G9a that is associated with cocaine-related changes in the nucleus accumbens, a brain region essential for the experience of desire, pleasure and drive. The role of the protein appears to be to shut down genes that shouldn’t be on. One-time use of cocaine increases levels of G9a. But repeated use works the other way, suppressing the protein and reducing its overall control of gene activation. Without enough G9a, those overactive genes cause brain cells to generate more dendritic spines, which are the parts of cells that make connections to other cells.
