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Fruit flies help explain why a male orgasm matters

Fruit flies help explain why a male orgasm matters
A red light made this fruit fly in the mood for a reward, teaching us the value of male ejaculation.

Yes, dear reader, fruit flies ejaculate.

And new research brings us this further news flash: They like it. It's what they like best about mating. So, that's the part of the whole courtship process that keeps them coming back for more. And more (ensuring the circle of life and all...).

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And that's enlightening because in man and fruit fly alike, the basic workings of reward are not so different. The principles by which rewards work, and even some of the mechanisms involved, are "conserved" — consistently seen in creatures up and down the evolutionary ladder.

So while the brains of human males are more complex than those of drosophila melanogaster (the common fruit fly), the simplicity of the latter can illuminate some fundamental truths about the former.

One of the truths that emerges from this study is that pleasure will not be denied. The male fruit fly will get it one way. Or he will get it another. And the alternatives to ejaculation he chooses may not always serve him so well.

In a study published Thursday in the journal Current Biology, Israeli researchers found that when there's no limit on a male fruit fly's access to the pleasure that comes with ejaculation, he makes good choices.

When he is denied those pleasures, not so much.

Faced with a buffet table of fruit-fly feeding options, the sexually satisfied fruit fly chooses the equivalent of a nice plate of chicken and salad with a glass of milk. When the pleasure of ejaculation has been in short supply, the fruit fly heads straight for the bar, choosing liquid food spiked with alcohol over the liquid food that is standard sustenance for fruit flies in the lab.

All of this actually helps explain not only what male humans enjoy (ejaculation), and why when such a powerful reward is absent, the human brain is more prone to engage in a scramble to either find it again or replace it with pleasure of another sort.

There are actually mysteries here. And here, they are being explored with a pretty new neuroscientific technique – optogenetics -- that you might not have taken the trouble yet to understand.

Now that sex is involved, maybe you'll be more motivated.

In this research, the Israeli neuroscientists genetically altered fruit flies in such a way that they could effectively pleasure themselves by flying into a zone bathed in red light.

In the abdomens of male drosophila lie brain cells which produce a pleasure protein called neuropeptide corazonin, which triggers the release of sperm and seminal fluid. Using optogenetics, the scientists rigged up a system in which fruit flies flying into red light would activate that neuropeptide, effectively ejaculating.

Over a few days, male fruit flies that had the chance flew repeatedly into the red light (evidence of the rewards that came with doing so). And in the brains of these sexually satified fruit flies, the authors of the study observed a growing reservoir of a protein they call neuropeptide F (the curious abbreviation they chose for Neuropeptide NPF, a key neurotransmitter in the fruit fly's simple nervous system). That's the same neuropeptide that builds up in male fruit flies who actually mated with female partners.

"The principles by which the brain processes reward are extremely conserved in all animals; this is a really basic everyday machinery that helps animals survive," said Galit Shohat-Ophir, a lecturer at Bar-Ilan University in Israel and one the authors of the new study. "Drugs of abuse use the same systems in the brain that are used to process natural rewards," she added.

Studying how a simple creature like the fruit fly responds to sex — and to a lack of it — may help inform research on drug addiction in humans, including the interplay between natural rewards like those that come with ejaculation and the ones that come with, say, opioid drugs or a belt of liquor.

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And that, said Shohat-Ophir, helps shed light on the mechanisms that underlie the risk of developing a drug addiction.

It also brings to mind (to this reporter, at least) the wisdom of Dr. Joycelyn Elders, whose tenure as U.S. surgeon general ended abruptly in 1994 after she suggested that masturbation was among the many sexual skills "that perhaps should be taught" as a means of keeping young people from riskier sexual activity.

She was fired for her remarks by President Clinton, whose risky sexual activity led to impeachment by the House of Representatives.

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