Rats Kick Cocaine Addiction With Help Of Lasers Shined On Their Brains

 @rpalmerscience
on April 03 2013 3:02 PM

Scientists have found a way to help cocaine-addicted rats kick the habit. The secret isn’t a tiny 12-step program; it’s a laser to the brain.

In a letter published in the journal Nature on Wednesday, University of California San Francisco neurologist, Antonello Bonci, and his team described how shining a light on a certain area in the frontal lobes of genetically engineered rats was able to switch off their cocaine-seeking behavior. The brain region of interest, the prefrontal cortex, is associated with impulse control and decision-making. Previous studies have found an association between low brain activity in the prefrontal cortex and cocaine addiction.

"When we turn on a laser light in the prelimbic region of the prefrontal cortex, the compulsive cocaine seeking is gone," Bonci, senior author and scientific director of the intramural research program at the National Institute of Drug Abuse, said in a statement.

What the light of the laser was doing was shutting the activity of certain nerve cells on and off. Neurons in the rats’ prefrontal cortex contained light-sensitive proteins called rhodopsins, thanks to a little genetic engineering. The rhodopsins could then be used like a switch for the nerve cells.

Some of the rats used in the study were so addicted to cocaine, they kept seeking it even when pursuing the drug meant receiving a painful electrical shock. Turning on the nerve cells cured the rats of their cocaine-seeking behavior, while switching the nerve cells off could transform a sober rat into a cocaine-addicted one.

Translating the therapy to humans would mean replacing the lasers with electromagnetic stimulation applied to the scalp. Bonci and his team are already working on trials in humans to see if this version of the treatment works.

An estimated 1.4 million Americans are addicted to cocaine, and the highly addictive drug is one of the top causes of heart attacks and strokes among people under 35.

It can be hard to break the chains of cocaine addiction, even with support groups, so many researchers have been attacking the problem from a medical angle.

One potential treatment is a vaccine. A version developed by Weill Cornell genetic medicine researcher Ron Crystal works by teaching the immune system to recognize cocaine as a threat. Inside the vaccine is a cocaine-like molecule linked to a piece of the virus that causes the common cold. Once in the patient's system, the cold virus provokes the immune system to produce antibodies against it. Thus alerted to cocaine, the immune system prevents the drug from crossing the blood-brain barrier, eliminating the high that comes when cocaine binds to parts of neurons involved in transporting dopamine.

Weill Researchers said they've found promising results with tests of the vaccine in mice and monkeys. However, even if an anti-cocaine vaccine is eventually approved in humans, it isn't a cure-all. Though it gets rid of cocaine's high, the vaccine doesn't protect against many of cocaine's side effects on the heart, lungs and circulatory system, researchers said.

SOURCE: Chen et al. “Rescuing cocaine-induced prefrontal cortex hypoactivity prevents compulsive cocaine seeking.” Nature published online 3 April 2013.

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