Stress, hangovers and alcoholism
Kofi
The World's No.1 Science & Technology News Service
ŚHangover geneą is key to alcohol tolerance
Updated 11:51 18 August 2005
NewScientist.com news service
Gaia Vince
A gene that helps fruit flies develop alcohol tolerance has been found
and named hangover. The gene also controls the fliesą response to
stress, and the researchers say that a similar pathway linking alcohol
tolerance and stress probably functions in humans.
The findings may explain why people who have been in a stressful
situation often have a blunted response to alcohol and may drink more to
feel inebriated, experts say, putting them at greater risk of becoming
addicted.
Ulrike Heberlein at the University of California at San Francisco, US,
and Henrike Scholz from the University of Würzburg in Germany, exposed
fruit flies to ethanol vapour. Intoxicated fruit flies show similar
behaviour to tipsy humans: they lack coordination and postural control
and then fall asleep. It took the flies an average of 20 minutes to
recover following their exposure.
After four hours on the wagon, the same Drosophila were again exposed to
alcohol. By now, they had developed a tolerance to alcohol and so needed
more to reach the same drunkenness, and took longer to dry out - 28
minutes.
But flies with a defective form of the hangover gene still took 20
minutes to recover from inebriation time after time - never building up
a tolerance.
Stressed out
The researchers then investigated how the gene was involved in stress
responses since, in humans at least, the alcohol and stress responses
appear to be linked.
A stress response was triggered in a new batch of fruit flies with
working hangover genes by heating them to 37C for 30 minutes. Four hours
later, the flies were exposed to alcohol and despite this being their
first alcoholic experience, they showed a high tolerance taking an
average of 29.5 minutes to sober up.
But the same increased alcohol tolerance was not seen when flies with
the defective gene were exposed to alcohol. There is growing recognition
that stress, at both cellular and systemic levels, contributes to drug-
and addiction-related behaviours in mammals. Our studies suggest that
this role may be conserved across evolution, Heberlein and Scholz
suggest.
The findings help to define the role that stress has in addiction, says
Leslie Morrow, at the Bowles Center for Alcohol Studies, University of
North Carolina, US. Prior stress can induce tolerance to alcohol even if
a person has never had a drink before. And that increased tolerance
means that a person can drink more and more before becoming inebriated,
making it more likely that they will end up with an addiction problem.
There may be people in the population who have an over-expression of the
human equivalent of the hangover gene and who may especially at risk
from developing addiction problems, Morrow adds.
Journal reference: Nature (vol 436, p 845)