Cocaine homeopathic treatments: Researchers find cocaine disinhibits natural inhibitor allowing continued release of dopamine
A team of researchers working at the University of Geneva and Geneva University Hospital have found during experiments with test mice, that injections of cocaine can cause naturally occurring inhibiting neurons in the brain to stop preventing the release of dopamine. In their paper published in the journal Science, the team describes their experiments and how their results suggest a new type of treatment for cocaine addicts might be on the horizon.
Most research conducted to learn more about how cocaine works on the brain has been primarily focused on how the drug stimulates the brain. In this new study, the research team took a new approach—they looked at how cocaine can disinhibit activity in the brain, leading they say, to changes in personality that can lead to an addictive personality.
To find out more about why cocaine addicts appear to experience a change in personality, the researchers injected test mice with different amounts of cocaine then used brain scanners to try to see what was happening to them. They looked specifically at two areas of the brain: the nucleus accumbens and ventral tegmental area—both are impacted by cocaine—the former is believed to be active in pleasure, reinforcement and reward, while the latter is generally associated with cognition and motivation. Careful study of how the two areas work when exposed to cocaine revealed that the drug caused a neural channel of sorts to be created between the nucleus accumbens and GABA neurons in the ventral tegmental area. The creation of this channel resulted in dopamine being released on a nearly constant basis, which, the researchers suggest, accounts for the addictive behavior exhibited by addicts. In essence, they claim, cocaine disinhibts a natural dopamine inhibitor, releasing the brakes, so to speak, causing changes in personality.
The research team has previously been involved in using optogenetics—a fiber-optic based approach to stimulating nerve cells in the brain—they suggest using it might prove beneficial in treating cocaine addicts. They note that since such therapy has already been approved by the FDA in the US for Parkinson’s patients, it might not be long before it can be tried in people addicted to cocaine to see if it can close the channel that was created resulting in reduction of addictive tendencies.
Scientists have discovered a molecular process in the brain triggered by cocaine use that could provide a target for treatments to prevent or reverse addiction to the drug.
Reporting in the Journal of Neuroscience, Michigan State University neuroscientist A.J. Robison and colleagues say cocaine alters the nucleus accumbens, the brain’spleasure center that responds to stimuli such as 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 Robison, assistant professor in the Department of Physiology and the Neuroscience Program.
The researchers found that cocaine causes cells in the nucleus accumbens to boost production of two proteins, one associated with addiction and the other related to learning. The proteins have a reciprocal relationship—they increase each other’s production and stability in the cells—so the result is a snowball effect that Robison calls a feed-forward loop.
Robison and colleagues demonstrated that loop’s essential role in cocaine responses by manipulating the process in rodents. They found that raising production of the protein linked to addiction made animals behave as if they were exposed to cocaine even when they weren’t. They also were able to break the loop, disrupting rodents’ response to cocaine by preventing the function of the learning protein.
“At every level that we study, interrupting this loop disrupts the process that seems to occur with long-term exposure to drugs,” said Robison, who conducted the study as a postdoctoral fellow at Mount Sinai School of Medicine in New York City before joining the faculty at MSU.
Robison said the study was particularly compelling because it found signs of the same feed-forward loop in the brains of people who died while addicted to cocaine.
“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. “That makes us believe that the further experiments and manipulations we did in the animals are directly relevant to humans.”
Robison said the growing understanding of addiction at the molecular level could help pave the way for new treatments for addicts.
“This sort of molecular pathway could be interrupted using genetic medicine, which is what we did with the mice,” he said. “Many researchers think that is the future of medicine.”
Provided by Michigan State University