By studying the effects of alcohol on fruit flies, scientists have discovered a gene that could lead to alcohol addiction.
The researchers have called the gene "hangover", and believe that a similar version may exist in humans which could explain why alcoholism seems to run in families.
The study found that the gene helps fruit flies to develop a tolerance to alcohol, a condition which in humans leads to dependency and addiction.
According to Ulrike Heberlein of the University of California in San Francisco, flies lacking the hangover gene do not develop the tolerance seen in those with the gene.
Dr Heberlein says that repeated alcohol consumption leads to the development of tolerance, which is simply defined as an acquired resistance to the physiological and behavioural effects of the drug.
It is this tolerance, she says that allows increased alcohol consumption, that eventually leads to physical dependence and addiction.
The scientists say that in nature, fruit flies are often exposed to alcohol in rotting fruit, and there is strong evidence to suggest that the drug has a similar effect on the insects.
Heberlein says that when flies are exposed to ethanol vapour, they become hyperactive, uncoordinated and eventually sedated.
In another discovery the research team found that, as well as making the flies more tolerant of alcohol, the hangover gene appeared to influence the way the insects responded to stressful conditions in their environment, such as increased temperature.
The scientists suspect that the gene may perhaps play a more general role in dealing with stressful conditions, and its influence on alcohol tolerance, is merely a side-effect.
It is therefore possible, say the scientists, that this might also happen in humans, suggesting that addiction may initially be triggered by the way in which the body responds to stressful factors, such as high alcohol intake.
The study is published in the journal Nature.
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