March 16, 2012
Spurned In Love, Study Finds Fruit Flies Turn To Alcohol
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A male, his affections spurned by a female that he's attracted to, is driven to excessive alcohol consumption. The story may be familiar, but in this case, the lead characters aren't humans -- they're fruit flies.
Researchers from the University of California, San Francisco (UCSF), have discovered that like their Homo sapiens counterparts, male members of the species Drosophila melanogaster tend to, for lack of a better term, "get drunk" after being rejected by females, according to Benedict Carey of the New York Times.
"Fruit flies apparently self-medicate just like humans do, drowning their sorrows or frustrations for some of the same reasons," Carey wrote on Thursday.
Male fruit flies that were rejected "preferred food spiked with alcohol far more than male flies that were able to mate" and drank "significantly more alcohol" than those who successfully mated, leading researchers to believe that "alcohol stimulates the flies' brains as a 'reward' in a similar way to sexual conquest," he added.
The research team, including Galit Shohat-Ophir, who now works at the Howard Hughes Medical Institute (HHMI) in Virginia, discovered that the behavior seems to be linked with a brain chemical called neuropeptide F (NPF), BBC News Science and Technology Reporter Jason Palmer said. He added that humans have a similar chemical in their brains known as neuropeptide Y (NPY), which has been linked to alcohol in previous studies.
"It is thought that reward systems evolved to reinforce behaviors that are important for the survival of both individuals and species, like food consumption and mating," Shohat-Ophir told Palmer.
"Drugs of abuse kind of hijack the same neural pathways used by natural rewards, so we wanted to use alcohol -- which is an extreme example of a compound that can affect the reward system -- to get into the mechanism of what makes social interaction rewarding for animals," she added.
According to Science Now reporter Sarah C. P. Williams, Shohat-Ophir and colleagues took 24 male fruit flies and placed them in one of two different situations. Four groups of four were each put in vials along with 20 female members of the species that were ready to mate.
This allowed the male flies to mate with multiple females, Williams said. Meanwhile, the other 12 were individually placed in vials along with a single female that had already mated and, as a result, would turn back the male fruit flies' advanced.
"After 4 days of repeated mating or rejection, the male flies were moved to new containers, with capillaries containing food mash -- some with alcohol and others without -- that they could eat. Each fly could chose which capillary to drink from, and the researchers measured the amount that was consumed," Williams said.
They discovered, according to AFP reports, that the male flies that had their sexual advances rebuffed had lowed NPF levels in their brains than those who had their desires fulfilled.
In fact, the study, which has been published this week in the journal Science, discovered that after their rejection, the unsatisfied fruit flies "gave up trying to mate altogether," the university said in a press release. "Even when placed in the same cage as virgin flies, they were not as keen to have sex."
Those results have led the UCSF scientists to predict that the study could ultimately lead to greater understanding of addiction in mankind. Lead researcher and anatomy and neurology professor Ulrike Heberlein said, “If neuropeptide Y turns out to be the transducer between the state of the psyche and the drive to abuse alcohol and drugs, one could develop therapies to inhibit neuropeptide Y receptors."
Clinical trials are currently underway to discover whether or not NPY delivery could be used to overcome anxiety and other mood disorders, as well as combat obesity, Heberlein said in a statement.