Anyone who is part of a rowdy New Year celebration knows that a little alcohol can make us euphoric, excited, and full of love. But the more we drink, the more we go down into a state of unconsciousness (sometimes life threatening). Scientists behind a recent study claim to have known how the initial feeling of humming happened, all thanks to some drunk fruit flies.
The study, published this month in the Journal of Molecular Biology, came on behalf of scientists at the Scripps Research Institute, a nonprofit research center and graduate school based in California and Florida.
Based on previous research, the team theorized that the effects of drowsy alcohol on the brain are similar to anesthesia. So they decided to carefully study the molecular pathways that are activated in nerve cells when we drink alcohol or undergo sedation, which involves the phospholipase D2 enzyme, or PLD2. PLD2 is thought to help connect ethanol molecules with fat stored in membranes, or surfaces, in nerve cells. And they use fruit flies as a substitute for people because flies really behave like we do when they drink.
"They act like humans," senior author Scott Hansen, a professor in the Department of Molecular Medicine at Scripps, said in a statement. "They began to lose coordination. They are really drunk. "
Hansen and his team put flies in a small tube and gave them liquid food that was given alcohol, and the flies were thought to be buzzing. When they looked at the brains of these flies afterward, they found that activation of PLD2 through alcohol caused a chain reaction from other processes in nerve cells. In particular, PLD2 breaks down alcohol into other molecules, or metabolites, and one of these metabolites is a molecule made from fat and alcohol called phosphatidylethanol (PEtOH). The accumulation of PEtOH in turn seems to encourage nerve cells to shoot more easily, which means their brain becomes hyperactive.
"With hyperactivity, you see more flies hanging around, and this is what we equate with hearsay," Hansen explained.
Hansen and his team also created flies that have genes that let their brain cells recognize PLD2 is turned off. These flies, unlike unchanging flies, did not act at all, supporting their case that PLD2 played an important role in creating an initial feeling that sounded drunk.
This finding is very interesting, the authors say, because alcohol is mostly thought to affect brain cells directly. But this will be an example of a drug that indirectly affects cells, via the PLD2 pathway. That is important because we are clearly interested in being able to stop the worst effects of alcohol on people. So, maybe a drug that can someday interact safely with PLD2 can stop us from getting drunk – which can help people who are dealing with alcohol dependence. Maybe stopping PLD2 can even prevent other negative aspects of drinking, such as brutal drunkenness.
"This definitely leads to several different ways of thinking about alcohol poisoning at the molecular level," Hansen said. "Most scientists think alcohol has a direct effect. Blocking an enzyme in a fly shows that it can't be true. "
Fruit flies are a useful substitute for humans, but of course, their brains are not like us. So there is a lot of work needed to find out whether PLD2 is a key player in making people buzz too. Hansen and his team also plan to continue to learn how important PLD2 is to help create the effects of other well-known alcohols, including sedation.[Journal of Molecular Biology via Scripps]