Cocaine addiction treatment could get easier, with the new discovery of a molecular brain process that's triggered by drug use. With more research, that process could be a target for preventing or reversing cocaine addiction.
Previous research has established significant brain differences in people with cocaine addictions. In particular, cocaine addiction causes long-term changes to the nucleus accumbens, the region of the brain that controls the pleasure that comes from indulging impulses like food, sex, and drugs.
"Understanding what happens molecularly to this brain region during long-term exposure to drugs might give us insight into how addiction occurs," said neuroscientist A.J. Robison of Michigan State University, who published the study in the Journal of Neuroscience.
Robison's research found that neurons in the nucleus accumbens produce higher levels of two proteins after cocaine use. One of the proteins is related to learning, and the other is related to addiction.
The two proteins complement each other in a positive feedback loop: each activates production of the other. The more someone uses cocaine, the more these proteins will be expressed.
The Michigan State researchers manipulated this feedback loop in rodents, in an effort to see how changes in the protein levels would alter the rats' cocaine addiction and addictive behavior.
They found that expressing higher levels of the addiction protein made the animals act like they were on cocaine, even when they had not taken any of the drug. Lower levels of the learning protein broke the positive feedback loop, so the rats did not respond typically to cocaine in their system.
Robison believes that interrupting the expression of these proteins could break the feedback cycle and aid cocaine addiction treatment.
Previous research on the brains of people with cocaine addiction showed evidence of the same positive feedback loop between these two proteins.
"The increased production of these proteins that we found in the animals exposed to drugs was exactly paralleled in a population of human cocaine addicts," he said in a statement.
"That makes us believe that the further experiments and manipulations we did in the animals are directly relevant to humans."
The finding could lead to new cocaine addiction treatments that alter the expression of these proteins, possibly by using gene therapy.