|Dr. Caroline E. Bass of the University at Buffalo is using light to influence brain cells.
“And then there was light.” And maybe an end to alcoholism?
NIH-supported scientists have demonstrated that stimulating specific brain cells of small animals with high-intensity light alters nerve cell activity and puts the brakes on alcohol consumption. If applicable to humans, this could point the way to strategies for treating alcohol abuse. The technique may also lead the way to new treatment approaches for other brain-associated disorders such as Parkinson’s disease, schizophrenia and various types of drug addiction, the scientists speculate.
Alcoholism and alcohol-associated disorders pose major health risks. Globally, alcohol use is the fifth leading risk factor for premature death and disability. Further, according to the National Institute on Alcoholism and Alcohol Abuse, drinking too much—on a single occasion or over time—can lead to accidents and dependence, damage organs, weaken the immune system and contribute to cancers. Also, imbibing excessively can worsen existing health problems, adds NIAAA, which reports that an estimated 17 million Americans have an alcohol use disorder (AUD)—a medical term that includes both alcoholism and harmful drinking that does not reach the level of dependence.
Binge drinking—consuming 5 or more drinks within 2 hours for men and 4 or more drinks during the same time for women—is extremely risky. While popular among adolescents and young adults, bingeing is common in all age groups. According to the Centers for Disease Control and Prevention, binge drinking is the most common pattern of alcohol abuse in the United States and likely the most perilous.
Numerous medications for treating alcohol dependence have become available in recent years and ongoing research continues to develop and explore new medications and other treatment approaches to expand treatment options for people with alcohol problems.
The current study is one new approach under investigation to advance our understanding of what happens in the brain in individuals with AUDs and to help develop potential treatments. With funding from two NIH sources—NIAAA and the National Institute on Drug Abuse, Dr. Caroline E. Bass, assistant professor of pharmacology and toxicology at the University at Buffalo, Evgeny Budygin from Wake Forest University and their colleagues investigated the effect of optogenetics—a technique that uses light to alter the activity of specific brain cells—on alcohol intake in rats that had been trained to consume alcohol in a way that parallels binge-drinking in humans.
“Specifically, what we did was to create a virus that delivers a light-sensitive gene which stimulates certain dopamine [a key brain chemical] neurons in a precise pattern at low, but prolonged levels,” Bass explained. “This resulted in the complete cessation of drinking behaviors in the rodent, which persisted even after the brain stimulation ceased.”
The beauty of optogenetics, Bass noted, is that it enables the scientist to stimulate one type of nerve cell at a time, unlike electrical brain stimulation, “which does not discriminate and thus affects all brain cells. The brain has many types of neurons and so optogenetics can be used to figure out which kind is contributing to a behavior or is malfunctioning in a disease.”
Development of such approaches is in sync with the Obama BRAIN Initiative, Bass added. She said optogenetics also lends itself to studying other disorders.
Meanwhile, a key question remains—why did the animals stop drinking? Bass said her team doesn’t fully understand the mechanism involved, though they think one likely scenario may be that dopamine spikes that normally occur with drinking cues (which initiates drinking) may be drowned out by the light treatment. “The dopamine release induced by the cues would be like throwing sand on a beach and, in this case, without the cues, the rats won’t start drinking.”
The investigators are cautiously optimistic that their animal research and optogenetics in general could point the way toward treatment options not only for alcoholism, but also for other brain-mediated conditions. Bass concludes that the ability to expose important brain pathways as targets for a drug, behavioral or biological treatment will probably yield the greatest clinical impact, though only after obstacles for treating humans (e.g., getting light into the human brain and targeting specific neurons) can be overcome.
The research was reported in a recent issue of Frontiers in Behavioral Neuroscience. Co-authors include Dr. Jeffrey Weiner, director of the NIAAA-funded Translational Centers for the Neurobehavioral Study of Alcohol.