Alcoholism may be in the genes, for flies

By Alison McCook

NEW YORK (Reuters Health) – Fruit flies carry a gene –
aptly named ‘hangover’ – that appears to help them become
tolerant to alcohol. Tolerance is thought to promote
dependence, so if a similar gene is found in humans, it might
lead to drugs to treat or prevent alcoholism.

In the journal Nature, researchers report that only fruit
flies that carry a functioning ‘hangover’ gene develop a
tolerance for alcohol.

“If humans have a gene that has a function similar to that
of ‘hangover,’ we could interfere with the function of such a
gene,” thereby preventing people from developing addiction to,
alcohol, study author Dr. Ulrike Heberlein of the University of
California at San Francisco told Reuters Health.

However, the researcher cautioned that this is still just
speculation.

During the study, Heberlein and colleagues mutated genes in
flies, then exposed them to alcohol. “When flies are exposed to
ethanol more than once they develop tolerance – i.e., it takes
higher alcohol levels to reach the same degree of
intoxication,” Heberlein explained. The researchers measured
how intoxicated flies become from alcohol using a device called
an inebriometer.

The found that flies that lacked a functioning hangover
gene did not develop a tolerance to alcohol – meaning that,
over time, they did not require more alcohol to become
intoxicated.

Co-author Henrike Scholz of the University of Wurzburg in
Germany explained that tolerance may lead to addiction because
when drinkers become tolerant to the positive effects of
alcohol, they need to drink more to feel good. Alternatively,
if people become tolerant to the negative effects of alcohol,
they can drink more without becoming sick, also increasing
consumption, Scholz noted.

And if alcohol alters brain function, it might program the
body to believe it can only function in the presence of
alcohol, Scholz added. “And therefore the brain might ‘tell’
the human being to continue drinking, although it might not be
good for the health of this human being,” the researcher told
Reuters Health.

Heberlein explained that the hangover gene in flies encodes
for a protein that regulates other genes. It’s not clear which
genes are regulated by the hangover gene, but they may help
flies respond to outside stressors, such as alcohol, Heberlein
noted.

Indeed, the researchers found that flies lacking the
hangover gene did not respond as well to heat and cell-damaging
free-radicals, supporting the theory that the gene helps
protect the body from environmental stress.

SOURCE: Nature, August 11, 2005.