Have pity on these poor fruit flies.
Researchers made a bunch of male fruit flies into boozehounds by pushing them on females unreceptive to their advances.
After a few days of striking out, the male losers, referred to as the "rejected-isolated" group in a study published online by Science, drowned their sorrows in alcohol.
They preferred food spiked with ethanol to their regular meal, and they were more likely to go for the alcohol than the males who'd had sex.
It's a sad experiment. And one that many of us have been subjected to in real life.
But this work conducted at the University of California, San Francisco, revealed more than that an age-old melodrama could be played out by fruit flies. The researchers showed that a chemical called neuropeptide F in the flies' brains played a key role in determining their behavior.
The less neuropeptide F was present in their little fly brains, the more likely they were to seek a drink. Being denied sex lowered neuropeptide F and increased their self-medication.
But there's a solution, and the researchers write dryly about it:
[T]he effects of sexual deprivation can be reversed by copulation, which is consistent with sexual deprivation being the major contributor to ethanol preference.
So having sex boosted neuropeptide F, decreasing the flies' interest in alcohol.
Very interesting for flies, you might say. So what?
Well, it turns we humans aren't sooooo different.
Humans' brains have got the same sort of chemical, called neuropeptide Y in our case, and it also looks like an important ingredient when it comes to our internal reward systems.
In humans, neuropeptide Y may be important in regulating stress and anxiety. When the chemical is out of whack, it may contribute to addictive behavior.
The experiments in flies show how social experiences may shape chemical dependence through changes in the level of neuropeptides.
Don't expect a drug or treatment for people based on neuropeptides anytime soon. It's not easy to get a molecule like that inside someone's brain, even if the science someday suggests that might be truly helpful.
Still, there have been some early experiments with neuropeptide Y, including one using it in a nasal spray as a potential treatment for post-traumatic stress disorder.