Optogenetics technique reverses effects of cocaine
A team of Swiss researchers has found the first link between cocaine use and physical brain changes, also finding a means to reverse it.
Led by Christian Lüscher of the University of Geneva (Geneva, Switzerland), the research team turned to optogenetics—a process that involves using certain kinds of algae with light-sensitive ion channels to cause some action in a cell in response to light—to both prove and counter the impact that cocaine has on the brain. In this case, it was used to reduce the firing potential of certain neurons brought about by the introduction of cocaine.
When cocaine is introduced into the brain, the firing potential of neurons of the nucleus accumbens (NAcc)—the part of the brain responsible for reward and pleasure—is increased. It has been suspected that this is what leads to the jittery behavior seen in addicts, though until now it has never been fully proven.
In their experiment, the team expressed such channels in cortical neurons that communicate with neurons in the NAcc in mice that had been given several rounds of cocaine to cause the change in brain activity. They then fired laser pulses at them to cause a virtual storm of chatter between the two cell types resulting in overkill, which caused them to reduce their firing on their own, effectively nullifying the initial impact caused by the cocaine.
By applying the procedure to several mice and finding virtually the same results each time (less brain chatter and less jittery behavior associated with cocaine use), the team has proven there is a link between the two.
However, this technique should not be mistaken as a means for helping addicts to stop using cocaine, as the technique only appears to work on the brains of mice that are newly addicted and whose brains haven’t been changed in other less-understood ways after extended drug use. So a true therapy is still in the distant future, the team notes; their next step is to see if they can find other brain changes due to drug use in mice to see if their process can undo those as well.
The team's work has been published in Nature; for more information, please visit http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10709.html.
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