Sex-starved fruit flies turn to alcohol, researchers findBy Eric BergerUpdated 11:31 p.m., Thursday, March 15, 2012 A male fruit fly drinks alcohol-laced food from a tube. Researchers say sexually deprived male fruit flies are driven to excessive alcohol consumption. Photo: G. Ophir / University of California, San Fr When spurned by a mate, male fruit flies will turn to drink.Scientists studying fruit fly behavior, both among the haves and have nots when it comes to sex, say only the rejected males showed a preference for alcohol in their food.Although it's tempting to speculate what frustrated flies turning to drink reveals about men, women and bars, scientists say the real value in the new research is that it brings us closer to understanding precisely how the minds of flies work.Flies may have smaller brains, with about 100,000 neurons compared to the 100 billion in a human brain, yet their neural circuitry is nonetheless illustrative of what happens inside the minds of humans.The stakes of this basic research in fruit flies are substantial, offering exciting prospects for understanding the molecular basis of human addictions."Understanding the molecular pathways that guide behavior in flies is a step toward fully understanding the more complex behaviors in mammals," said Gregg Roman, a biologist at the University of Houston who works with fruit flies.Substitute for sex?The study, done at the University of California San Francisco's Heberlein lab, sought to investigate whether rejection during courtship would change whether flies consumed alcohol.In their experiment, the researchers found that flies who had a successful mating - the courtship takes about 10 minutes, on average, and the copulation itself 20 minutes - consumed equal amounts of food containing ethanol, and food without it."But to our surprise the rejected males had much higher consumption of the food with alcohol," said the study's lead author, Galit Shohat-Ophir, now of the Howard Hughes Medical Institute in Virginia.The researchers, whose study was published Thursday in Science, said they were not expecting rejected flies to seek consolation from alcohol.When they investigated the neuroscience behind this, the researchers found that the same neuropeptide - a protein used by neurons to "communicate" with one another - was involved in sex as well as alcohol consumption in flies.Thus the flies appear to have substituted alcohol for sex.Mammals including mice and humans have a similar neuropeptide at work in their brains. Previous research has shown, for example, that eliminating the production of this neuropeptide in mice increases their alcohol consumption.The human nervous system is clearly more complex than that of flies', but researchers believe this kind of work will yield a more comprehensive understanding of the mechanics of addiction, allowing doctors to better treat human addictions, such as drugs, food and sex. For example, if a physician knows whether a lack or abundance of a particular neuropeptide is causing an alcoholic to binge, steps can be taken to get the neuropeptide to its proper level.'Evolutionarily linked'Scientists who work with fruit flies say the study also provides a moment for people to step back and marvel at the humble fly. It's not, after all, a little automaton, scurrying around."If you ask a person on the street, 'Do you function on a molecular level the same way as a fruit fly,' what do you think they will say?" asked Dr. Herman Dierick, a neuroscientist at Baylor College of Medicine.Most people would probably answer no, he said. But in reality, scientists are finding that the molecules that regulate actions in flies are remarkably similar in higher organisms."For some it may be remarkable that we see these similarities," he said. "But it's only natural as we're all evolutionarily linked."
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