Published August 1, 2012
A UB researcher and his collaborators have found that chronic
exposure to cocaine reduces the expression of a protein known to
regulate brain plasticity—a finding that suggests a potential
new target for treating addiction to the drug.
The researchers’ molecular studies show that a reduction
in expression of the protein, called Rac1, drives structural
changes in the brain that increase its sensitivity to
cocaine’s rewarding effects.
Among the most important changes is the large increase in the
number of physical protrusions, or spines, that grow out from the
neurons in the brain’s reward center. The spines’
presence demonstrates the spike in the reward effect that an
individual receives from cocaine exposure.
“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,” says David
Dietz, PhD, assistant professor of pharmacology and
toxicology, who conducted the research while at Mount Sinai
School of Medicine.
By changing the level of expression of Rac1 in mice, Dietz and
his colleagues were able to control whether or not they became
The researchers conducted the experiment with a novel tool that allowed for light activation to control Rac1 expression—the first time that a light-activated protein has been used to modulate brain plasticity.
“We can now understand how proteins function in a very temporal pattern, so we could look at how regulating genes at a specific time point could affect behavior, such as drug addiction, or a disease state,” says Dietz.
Dietz is continuing his research on the relationship between behavior and brain plasticity at UB. He and his team are looking at how plasticity might determine how much of a drug an animal takes and how persistently the animal tries to get the drug.
The study was published in Nature
Neuroscience in an article titled “Rac1
is essential in cocaine-induced structural plasticity of nucleus
Institute on Drug Abuse and the National Institute of Mental
Health funded the research.