The bar flies
The first port of call for human beaus whose object of desire has turned them down is often a local bar to drown their sorrows - and it turns out we're not alone.
Male fruitflies also tend to hit the bottle when they are unlucky in love, researchers say.
In lab tests, flies who had been rejected by females turned to booze - slurping down a syrup as strong as fortified wine to help them cope.
Researchers at the University of California found that a 'switch' in their brains turns the insects to the bottle - and that the finding could be used to stop humans doing the same.
The University of California team found a tiny molecule in the fly's brain called neuropeptide F changes when they are denied sex. This leads them to drink more.
A similar human molecule, called neuropeptide Y, may likewise work as a 'trigger' for behaviours like excessive drinking and drug abuse.
Dr Galit Shohat-ophir said: 'It's a switch that represents the level of reward in the brain and translates it into reward-seeking behaviour.' Adjusting its levels in people may alter their addiction - which is exactly what the researchers observed in the fruit flies.
Prof 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.'
She added that clinical trials are underway to test whether delivery of neuropeptide Y can alleviate anxiety and other mood disorders as well as obesity.
The study published in Science placed male fruit flies in a container with either virgins or females that had already mated.
While virgins readily mate and are receptive toward courting males, afterwards they lose their interest in sex for a time.
The rejected males then gave up trying to mate altogether, but their drinking behaviour also changed. When placed by themselves in a new container and presented with two straws, one containing plain food and the other food supplemented with 15 percent alcohol, the sexually rejected flies binged on the alcohol, unlike those that had been sexu- ally satisfied.
The researchers showed they could induce the same behaviors by genetically manipulating the neuropeptide F levels in the flies' brains. Activating the production of neuropeptide F in the brains of virgin males flies made them act as if they were sexually satisfied, and they voluntarily curtailed their drinking.
Lowering the levels of the neuropeptide F receptor made flies that were completely sexually satisfied act as if they were rejected, inciting them to drink more.
The finding has great relevance to addressing human addiction, though it may take years to translate this discovery into any new therapies for addicts, given the much greater complexities of the human mind. Already, scientists know levels of neuropeptide Y are reduced in people who suffer from depression and post-traumatic stress disorder, conditions that are also known to predispose people toward excessive alcohol and drug abuse.
Manipulating neuropeptide Y may not be so straightforward, however, since the molecule is distributed all over the human brain, and based on rodent studies, it has roles in feeding, anxiety and sleep, in addition to alcohol consumption.