After a long and unforgiving week, the weekend has finally arrived and, with it, a whole slew of parties, filled with libations and fellow single college students. When the night turns out to be not as successful as planned, you retreat to the bar or your single-not-by-choice den and drown your sorrows in some more libations (provided that you’re 21 or older, of course). Sound familiar?
While it’s easy to conceive how this behavior could result from social convention, wherein alcohol replaces a human relationship, recent research from the University of California in San Francisco suggests that there’s more to it—it’s biological. How did the researchers reach this conclusion? Fruit flies do it, too.
Headed by neuroscientist Galit Shohat-Ophir, researchers at UCSF have discovered that sexually rejected male fruit flies are more likely to ingest alcohol than non-rejected males, which is the first evidence of social interaction impacting future behavior in fruit flies. Before planning this “wild experiment,” Shohat-Ophir knew from previous literature that consuming alcohol activated reward pathways in the flies’ brains, giving them a sense of pleasure akin to that in humans, but she did not anticipate the “dramatic results” that were found.
Twenty-four male fruit flies were divided into two equal groups; one half were further separated into groups of four, each cluster in a separate vial containing twenty female flies. Under these conditions, these males were able to mate with multiple females. On the other hand, the second half were kept alone in vials with only one female that was not ready to mate, having already copulated with another. After four days in these experimental conditions, the flies were transferred to containers with a mix of alcohol-soaked and normal food mash in separate capillaries.
Based on measurements of how much the flies ate, researchers reported in Science that 1) sexually rejected males preferred the alcohol-soaked mash to the non-alcoholic food 2) sexually accepted males had an aversion to the alcoholic mash. Overall, rejected males drank about four times more alcohol than the accepted flies.
Given these results, the scientists also measured levels of neuropeptide F (NPF), a chemical in the brain known to regulate alcohol preference. Indeed, the sexually rejected males had about half as much NPF as the mated males, and decreasing the amount of NPF receptors in mated males increased their alcohol preference. This indicates that NPF controls drinking behavior by encouraging the flies to activate their reward systems.
Shohat-Ophir points out that these findings could potentially help us understand how complex behaviors, including reward behavior, are processed in the brain. Since mammals have a protein known as neuropeptide Y (NPY) that functions quite similarly to NPF, this claim doesn’t seem too far off. She notes, however, “Our results certainly don’t translate directly from flies to humans.”
In any case, this extremely fascinating study may offer hope to bachelor(ettes) with a proclivity for drinks: flies know your pain.