In the world many people have some perception that heavy drinking and sex go hand. However, a team of researchers at UC San Francisco have revealed on their publication in the latest issue of Science.
Their study concluded that male fruit flies get frustrated to sexual rejection.
When their attempts at courtship fail, the spurned male flies will actually turn to booze as a substitute for sex. Understanding this kind of behaviour, one could allow us humans to sort out some of our own dependencies.
Fruit flies are very sexual beings. Put a randy male fly in close quarters with a female, and (provided the male does a halfway decent job of wooing his counterpart) the two will copulate.
Things pan out a little differently, however, if the female has already mated. If this is the case, she will refuse the male's advances at all costs including running away, kicking, and even thrusting out herovipositor (an organ typically used for egg-laying) in protest.
The study revealed that when given the choice, rejected male flies prefer food that has been spiked with alcohol over their normal grub. Males that had successfully mated, on the other hand, showed no preference for one meal or the other.
In this study, a team of researchers used this behaviour to identify a signalling molecule in the flies' brains called neuropeptide F(NPF).
Flies that had been denied sex were shown to have low levels of NPF; but when researchers genetically altered sex-deprived flies to produce NPF at higher levels than usual, they behaved as though they were sexually satisfied, and demonstrated no preference for alcohol-dosed food.
"Natural rewards and abused drugs affect the function of the brain's reward systems”, to make this clear, after an elaborate courtship ritual by a male, rejection by a female, or sexual deprivation, decreases the amount of neuropeptide F in the male fly brain.
This correlates with the male's increased preference for ethanol, a behaviour associated with reward and reward seeking. Therefore, abnormal function of these brain regions is associated with addictive behaviour. In the case of the male fruit flies, the neural pathway that NPF uses to reinforce and reward sexual experiences has been linked to alcohol consumption.
NPF is similar to a signalling molecule in humans called neuropeptide Y. By shedding light on the relationship between NPF and neurological reward systems linking sex and alcohol consumption, the research team believes they can gain a better understanding of how addiction works in humans.