Researchers Say Chronic Cocaine Uses Changes Brain's Neuron Structure

Posted on May 13, 2012

Researchers at the University at Buffalo and Mount Sinai School of Medicine say they have found through experiments with mice that chronic cocaine use reduces the expression of a protein known to regulate brain plasticity. This reduction drives structural changes in the brain, which produce greater sensitivity to the rewarding effects of cocaine. The brain changes observed in the mice included the growth of physical protrusions or spines in the reward center of the brain. The research was published here in Nature Neuroscience.

David Dietz, PhD, assistant professor of pharmacology and toxicology in the School of Medicine and Biomedical Sciences, who did the work while at Mt. Sinai, says, "We found that chronic cocaine exposure in mice led to a decrease in this protein's signaling. The reduction of the expression of the protein, called Rac1, then set in motion a cascade of events involved in structural plasticity of the brain -- the shape and growth of neuronal processes in the brain. Among the most important of these events is the large increase in the number of physical protrusions or spines that grow out from the neurons in the reward center of the brain. This suggests that Rac1 may control how exposure to drugs of abuse, like cocaine, may rewire the brain in a way that makes an individual more susceptible to the addicted state."

The presence of the spines demonstrates the spike in the reward effect that the individual obtains from exposure to cocaine. By changing the level of expression of Rac1, Dietz and his colleagues were able to control whether or not the mice became addicted, The researchers say this could lead to a potential new target for development of a treatment for cocaine addiction.