Summary: New research reveals why alcohol makes people feel happier in social settings but not when drinking alone. Using fruit flies, scientists discovered that dopamine in the brain plays a key role in amplifying the euphoric effects of alcohol during social interactions.
The study highlights the D1 dopamine receptor’s involvement in alcohol’s impact on the brain, offering insights into vulnerability to Alcohol Use Disorder (AUD). This finding could pave the way for better understanding and treatment of AUD.
Key Facts:
- Social Drinking and Dopamine: Social settings enhance the euphoric effects of alcohol through increased dopamine activity, while solitary drinking results in a less significant mood boost.
- Fruit Fly Model: Fruit flies share 75% of genes with humans, making them an effective model for studying alcohol’s impact on behavior and brain activity.
- D1 Dopamine Receptor: The D1 receptor is a crucial component in the brain’s response to alcohol in social settings, potentially linked to Alcohol Use Disorder.
Source: UT El Paso
Grab a drink with friends at happy hour and you’re likely to feel chatty, friendly and upbeat. But grab a drink alone and you may experience feelings of depression. Researchers think they now know why this happens.
“Social settings influence how individuals react to alcohol, yet there is no mechanistic study on how and why this occurs,” said Kyung-An Han, Ph.D., a biologist at The University of Texas at El Paso who uses fruit flies to study alcoholism.
Now, Han and a team of UTEP faculty and students have taken a key step in understanding the neurobiological process behind social drinking and how it boosts feelings of euphoria.
Their new study, published in a recent issue of the journal Addiction Biology, pinpoints the region of the brain that is stimulated by social drinking and may lead to a better understanding of how humans become vulnerable to Alcohol Use Disorder (AUD), a disease that affected nearly 29.5 million people just this past year, according to the National Institute on Alcohol Abuse and Alcoholism.
Turns out that tipsy fruit flies aren’t that different from intoxicated humans. Although they might seem like an unconventional choice from which to derive knowledge about human behavior, these insects share about 75% of the same genes that cause human diseases, Han explained.
Using fruit flies, Han and her team sought to demonstrate that ethanol, the alcohol in drinks, causes different reactions in solitary versus group settings and that dopamine, the brain molecule that plays a role in pleasure, motivation and learning, is a key player for this phenomenon.
The team’s experiments consisted of exposing fruit flies, either alone or in a group setting, to ethanol vapor and measuring their average speed to determine the degree of ethanol-induced response. While flies who “drank alone” displayed a slight increase in movement, flies exposed to ethanol in a group setting displayed significantly increased speed and movement.
The team then proceeded to test whether dopamine plays a role in the flies’ response to ethanol, comparing a control group whose dopamine was naturally regulated by the brain with an experimental group that had increased levels of dopamine.
The team found that the flies, regardless of whether they had normal or increased levels of dopamine, had a similar reaction to ethanol in a solitary setting — a tiny increase in activity. But in social settings, the flies with increased dopamine showed even more heightened hyperactivity than usual.
“We demonstrated that both social settings and dopamine act together for the flies’ heightened response to ethanol,” said Han who currently serves as associate dean in the College of Science.
The team’s final task was to identify which of the five dopamine receptors in the brain is the largest contributor in this process and found that the D1 dopamine receptor was most important to flies’ reaction to ethanol in a social setting.
“The human D1 receptor gene is linked to Alcohol Use Disorder and this study provides experimental validation for it. For the team, the identification of the D1 receptor is crucial as it gives researchers at UTEP and beyond a blueprint for follow up studies,” Han explained.
“Our work is providing scientific knowledge to support the idea that the brain interprets and processes a person’s social surrounding and has that signal converge into the dopamine system that is also activated by alcohol consumption,” said Paul Rafael Sabandal, Ph.D., a research assistant professor in biological sciences and one of the study’s corresponding authors.
“It gives us as researchers an idea of which brain area and components may serve as the meeting point for all the signals that contribute to AUD.”
The team’s next step is to explore the intricacies by which the D1 dopamine receptor serves as the nexus point for the signals that contribute to the ethanol, social interaction and AUD.
Han said, “The opportunity to work on projects whose positive impact can be applied at scale is one of the reasons I became a scientist. It’s humbling to know that our work has the potential to help people live better lives and our team is going to continue striving toward achieving that goal.”
Additional study authors are former UTEP undergraduates Dilean Murillo Gonzalez and Bryan Hernandez Granados, who are now at the Baylor College of Medicine Neuroscience Graduate Program and the Vanderbilt University Postbaccalaureate Program, respectively.
Funding: The research was funded by UTEP’s Orville Edward Egbert, M.D. Endowment fund.
About this social neuroscience research news
Author: Victor Arreola
Source: UT El Paso
Contact: Victor Arreola – UT El Paso
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Social setting interacts with hyper dopamine to boost the stimulant effect of ethanol” by Kyung-An Han et al. Addiction Biology
Abstract
Social setting interacts with hyper dopamine to boost the stimulant effect of ethanol
Alcohol consumption occurring in a social or solitary setting often yields different behavioural responses in human subjects. For example, social drinking is associated with positive effects while solitary drinking is linked to negative effects.
However, the neurobiological mechanism by which the social environment during alcohol intake impacts on behavioural responses remains poorly understood.
We investigated whether distinct social environments affect behavioural responses to ethanol and the role of the dopamine system in this phenomenon in the fruit fly Drosophila melanogaster.
The wild-type Canton-S (CS) flies showed higher locomotor response when exposed to ethanol in a group setting than a solitary setting, and there was no difference in females and males.
Dopamine signalling is crucial for the locomotor stimulating effect of ethanol. When subjected to ethanol exposure alone, the dopamine transport mutant flies fumin (fmn) with hyper dopamine displayed the locomotor response similar to CS.
When subjected to ethanol in a group setting, however, the fmn‘s response to the locomotor stimulating effect was substantially augmented compared with CS, indicating synergistic interaction of dopamine signalling and social setting.
To identify the dopamine signalling pathway important for the social effect, we examined the flies defective in individual dopamine receptors and found that the D1 receptor dDA1/Dop1R1 is the major receptor mediating the social effect.
Taken together, this study underscores the influence of social context on the neural and behavioural responses to ethanol.
