Investigators in the United States have determined how repeated exposure to cocaine leads to an impaired sense of reward in the human brain. This mechanism culminates in reducing the feelings of reward or pleasure from all other activities except cocaine use.
What scientists found was that the drug influences a specific protein, a molecule that plays an important role in supporting the normal operation of neurons in the brain's reward system. The chemical also boosts the pleasure response users get from consuming heroin.
This boost is one of the main reasons that cocaine becomes addictive so fast. The most significant finding in this study is that blocking the actions of cocaine on this protein can prevent addiction.
The new investigation, which was conducted on unsuspecting lab mice, is the first ever to show the exact changes that cocaine induces on the shape and size of reward neurons. Details of the study were published in the April 22 online issue of the top journal Nature Neuroscience.
The main implication here is that researchers at the Mount Sinai Medical Center, in New York, may have just found a new way of addressing cocaine addiction. The method is still far from practical implementation in the clinic, but early results are very promising.
“There are virtually no medication regimens for cocaine addiction, only psychotherapy, and some early work with vaccines,” says the MSMC Nash Family professor of neuroscience, Eric Nestler, MD, PhD.
The expert was the senior investigator on this research. He also holds appointments as the Chairman of the Neuroscience, and the director of the Friedman Brain Institute, at the Mount Sinai School of Medicine. He adds that the target protein is called Rac1.
Scientists conducted this work utilizing a version of the molecule that could be controlled using light. This capability is achieved by using a special marker, which responds to a specific wavelength. This area of study is called optogenetics.
“The research gives us new information on how cocaine affects the brain's reward center and how it could potentially be repaired,” Dr. Nestler explains, quoted by EurekAlert
“This is the first case in the brain in vivo where it's been possible to control the activity of a protein, inside nerve cells in real time. Our findings reveal new pathways and target – a proof of principle study really – for treatment of cocaine addiction,” the investigator concludes.