For
hardened drinkers, it sounds too good to be true: a natural substance that
keeps them sober no matter how much they drink, neutralises hangovers and
eventually breaks the cycle of alcohol addiction.
Won't make
any difference
(Image: OJO Images/Rex Features )
|
Alcoholism
is a huge problem globally, killing 2.5 million people a year according to the World Health Organization. There has been serious research recently looking for
drugs that stop people drinking, or at least encourage them to drink less.
Extracts of
a Chinese variety of the oriental raisin tree (Hovenia dulcis) could be the
answer. The extracts have been used for 500 years to treat hangovers in China.
Now dihydromyricetin (DHM), a component of the extract, has proved its worth as
an intoxication blocker in a series of experiments on boozing rats. It works by
preventing alcohol from having its usual intoxicating effects on the brain,
however much is in blood.
Soon, a
preparation containing DHM will be tested for the first time in people. "I
would give it to problem drinkers who can't resist going to the pub and
drinking," says pharmacologist Jing Liang of the University of California,
Los Angeles, who led the research team.
"DHM
will reduce the degree of drunkenness for the amount of alcohol drunk and will
definitely reduce the hangover symptoms," says Liang. "In time, it
will reduce their desire for alcohol."
Too drunk
to stand
Liang first
tested whether DHM blocks the clumsiness and loss of coordination caused by
drinking too much. To do this, she measured how long it took for treated rats
to right themselves after being laid on their backs in a V-shaped cradle.
After she
injected rats' abdomens with a dose of alcohol proportionate to the amount a
human would get from downing 15 to 20 beers in 2 hours by a human, they took
about 70 minutes, on average, to right themselves. However, when an injection
of the same amount of booze included a milligram of DHM per kilogram of rat
body weight, the animals recovered their composure within just 5 minutes.
DHM also
stopped rats in a maze from behaving in ways resembling anxiety and hangovers.
Rats given heavy doses of alcohol cowered away in corners of the maze, whereas
those given the extract with their alcohol behaved normally and were as inquisitive
as rats given no alcohol at all, exploring the more open corridors of the maze.
Finally,
DHM appeared to discourage rats from boozing when they had a free choice
between drinking a sweetened solution of alcohol or sweetened water. Over a
period of three months, rats will normally get addicted to increasing volumes
of the hard stuff. Rats given DHM, though, drank no more than about a quarter
of the amount that the "boozers" eventually built up to. Moreover,
boozy rats that had worked up to the higher levels suddenly dropped down to a
moderate intake when given DHM after seven weeks.
All the
benefits of DHM were lost instantly when Liang also gave the rats a drug called
flumazenil, which is known to block receptors in the brain for a
neurotransmitter called gamma aminobutyric acid (GABA). According to Liang,
this proved that DHM works by stopping alcohol from accessing the same
receptors. This, she says, explains why DHM kept the rats sober even when they
had huge amounts of alcohol in their blood.
Good idea?
"This
supports other data that GABA receptors are key in the actions of alcohol and
that targeting this interaction is a viable approach to reducing alcohol
intake," says David Nutt of Imperial College London, former head of the
British government's advisory committee on drugs. "Let's hope it's safe to
use in humans."
Other
alcohol experts fear that the availability of a "sobriety pill" could
encourage more, not less drinking. Markus Heilig, clinical director of the US
National Institute on Alcohol Abuse and Alcoholism in Bethesda, Maryland, says
that Roche abandoned development of a similar compound called Ro15-4513.
"There was a lot of philosophical worry that an 'alcohol antidote' would
entice people to consume alcohol and then count on being able to terminate the
intoxicating effects on demand," says Heilig.
Ro15-4513
caused serious side effects, including anxiety and convulsions. Liang says
there is no sign that DHM carries similar side effects.
Journal
reference: The Journal of Neuroscience, DOI: 10.1523/jneurosci.4639-11.2012
No comments:
Post a Comment