Pubdate: Wed, 07 Sep 2005
Source: Guardian, The (UK)
Copyright: 2005 Guardian Newspapers Limited
Contact:  http://www.guardian.co.uk/guardian/
Details: http://www.mapinc.org/media/175
Author: Alok Jha, science correspondent
Bookmark: http://www.mapinc.org/pot.htm (Cannabis)

CANNABIS JOINS BATTLE OF THE BULGE

The Drug That Gives Smokers The Munchies Could Also Suppress
Hunger

Scientists have unveiled an unlikely weapon in the battle against the
bulge: cannabis. More specifically, one of its key ingredients, which
has been found to suppress appetite.

Anyone who has ever inhaled will know the feeling: an inescapable
desire to eat everything in sight, a state called the munchies. It
stems from the action of tetrahydrocannabinol (THC), one of the active
ingredients in cannabis, on specific appetite-control receptors in the
brain. The chemical also causes the body to lay down more fat.

But Roger Pertwee, a neuropharmacologist at Aberdeen University, said
yesterday at the British Association festival of science that there is
more to the cannabis story.

"We've discovered to our surprise that cannabis, as well as containing
a drug that boosts appetite, contains a drug which has a blocking
effect," said Professor Pertwee. "The work so far has been working
with tissue and we've yet to see what this drug does when we give it
to a whole organism and what it does when we give it to humans."

The drug, known as tetrahydrocannabivarin (THCV), works on the same
receptors as THC but has entirely the opposite effect. The research
will be published in the British Journal of Pharmacology.

THCV is not the first appetite suppressant to be inspired by cannabis.
The drug Rimonabant works by blocking the brain receptors that the
body's own cannabinoid compounds - released when we comfort eat -
attach themselves to. Because the cannabinoids do not reach the
receptors in a person taking Rimonabant, they will feel less
compulsion to eat.

Why THCV does not manifest itself to people who smoke cannabis is a
mystery, but Prof Pertwee said it might have something to do with the
proportions of the various ingredients in the drug. "The relative
proportions of THC and THCV vary from cannabis to cannabis," he said.

"There is a large amount of THCV in Pakistani cannabis, which is the
one used to make a medicine called 'tincture of cannabis'. That
contained about equal amounts of THC and THCV."

Prof Pertwee said that there were several promising medicinal
compounds to be derived from cannabis, both for boosting the effects
of the body's own cannabinoids and for blocking them.

Boosting the cannabinoids could bring pain relief, for example, and
relieve spasms for sufferers of multiple sclerosis. Prof Pertwee added
that there was also evidence that the compounds had a protective
effect against cancer.

As well as controlling appetite, developing drugs that block the
body's cannabinoids could help people to quit smoking by stopping
nicotine having any effect on the brain.
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