Published February 3, 2014
Novel research by a University at Buffalo scientist demonstrates a causal relationship between the release of dopamine in the brain and drinking behaviors of animals.
The study, led by first author Caroline E. Bass, PhD, assistant professor of pharmacology and toxicology, could lead to powerful new ways to treat addictions, neurological diseases and mental illnesses.
Bass and her colleagues successfully changed alcohol-drinking behavior in rodents using emerging optogenetic techniques to stimulate neurons with light.
Their findings, which help explain the underlying neurochemical basis of alcohol addiction, have been published in Frontiers in Behavioral Neuroscience.
The researchers first trained rats to drink alcohol in a way that mimics human binge-drinking behavior, then focused on prevention.
“By stimulating certain dopamine neurons in a precise pattern, resulting in low but prolonged levels of dopamine release, we could prevent the rats from binging,” Bass explains.
“The rats just flat out stopped drinking,” she says, adding that they continued to avoid alcohol even after the stimulation of neurons ended.
“For decades, we have observed that particular brain regions light up or become more active when an alcoholic drinks or looks at pictures of people drinking, for example, but we didn’t know if those changes in brain activity actually governed the alcoholic’s behavior,” says Bass.
The researchers activated the dopamine neurons through optogenetics, a type of deep brain stimulation that uses light instead of electricity to stimulate neurons.
“Optogenetics allows you to stimulate only one type of neuron at a time,” says Bass.
“Unlike optogenetics, electrical stimulation doesn’t discriminate,” she says. Although electrical simulation hits all the neurons, the brain has many different kinds of neurons, with different neurotransmitters and different functions, she explains.
Bass, who specializes in creating viral vectors, used a virus to introduce a gene encoding a light-responsive protein into the rodents’ brains.
That protein then activated a specific subpopulation of dopamine neurons in the brain’s reward system.
“I created a virus that will make this protein only in dopaminergic neurons,” she explains.
The neuronal pathways affected in Bass’ research also are involved in a number of neurological disorders, so her results can be used to understand and possibly treat diseases with a dopamine component.
“We can target dopamine neurons in a part of the brain called the nigrostriatal pathway, which is what degenerates in Parkinson’s disease,” she says.
“If we could infuse a viral vector into that part of the brain, we could target potentially therapeutic genes to the dopamine neurons involved in Parkinson’s.”
By infusing the virus into other areas of the brain, researchers could potentially deliver therapeutic genes to treat other neurological diseases and mental illnesses, including schizophrenia and depression.
Research like Bass’ makes it possible to map the neuronal circuits responsible for specific behaviors.
Such studies are a major focus of President Barack Obama’s Brain Research for Advancing Innovative Neurotechnologies initiative.
Bass collaborated on the research with colleagues from Wake Forest University in North Carolina, where she worked previously, and the University of North Carolina Neuroscience Center.
The research was funded by the National Institutes of Health.