Chronic exposure to cocaine reduces the expression of a protein known to regulate brain plasticity, which in turn triggers structural changes in the brain. That's according to University at Buffalo neuroscientists, who add that the structural changes produce greater sensitivity to the rewarding effects of cocaine.
"We found that chronic cocaine exposure in mice led to a decrease in this protein's signaling," says researcher David Dietz. "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... 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.
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 was able to control whether or not the mice became addicted, by preventing enhancement of the brain's reward center due to cocaine exposure.
Dietz says Rac1 may control how drugs of abuse, like cocaine, rewire the brain in a way that makes an individual more susceptible to the addicted state. The finding suggests a potential new target for development of a treatment for cocaine addiction. "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," says Dietz.
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Source: University at Buffalo