Pubdate: Wed, 06 Apr 2005
Source: Atlanta Journal-Constitution ( GA )
Copyright: 2005 The Atlanta Journal-Constitution
Contact: http://www.ajc.com/opinion/content/opinion/letters/sendletter.html
Website: http://www.accessatlanta.com/ajc/
Details: http://www.mapinc.org/media/28
Author: Malcolm Ritter
Bookmark: http://www.mapinc.org/mmj.htm (Cannabis - Medicinal)

MARIJUANA INGREDIENT SLOWS HEART DISEASE PROGRESSION IN MICE

Low doses of the main active ingredient in marijuana slowed the progression 
of hardening of the arteries in mice, suggesting a hint for developing a 
new therapy in people.

Experts stressed that the finding does not mean people should smoke 
marijuana in hopes of getting the same benefit.

"To extrapolate this to, 'A joint a day will keep the doctor away,' I think 
is premature," said Dr.  Peter Libby, chief of cardiovascular medicine at 
Boston's Brigham and Women's Hospital.

The mouse work is presented in Thursday's issue of the journal Nature by 
Dr.  Francois Mach of Geneva University Hospital in Geneva, Switzerland, 
and colleagues.  He said in an e-mail that he believed future work will 
focus on finding drugs that mimic the benefit without producing marijuana's 
effects on the brain.

Hardening of the arteries sets the stage for heart attacks.  Inflammation 
plays a key role in the condition, characterized by a progressive buildup 
on the inside walls of blood vessels.  So Mach and colleagues explored the 
anti-inflammatory effects of marijuana's main active ingredient, 
delta-9-tetrahydrocannabinol, or THC.

They fed mice a high-cholesterol diet for 11 weeks.  About halfway through 
that period, they started giving some of the mice very low, daily oral 
doses of THC ? too low to produce any marijuana-like changes in 
behavior.  At the end of the experiment, mice that had gotten the THC 
showed less blood vessel clogging than did mice that got no THC.

Related work showed no additional benefit from higher THC doses, such as a 
person would get from smoking marijuana, Mach noted.

Researchers found that the benefit came from THC's effect on immune-system 
cells.  It reduced their secretion of an inflammation-promoting substance 
and their migration to the vessel wall, researchers found.

It apparently did that by binding to proteins called CB2 receptors, which 
are found mostly on immune-system cells.  THC also targets CB1 receptors, 
found mostly in the brain.  So the work suggests scientists should try to 
develop a drug that works on CB2 receptors while ignoring the brain 
receptors, Mach said.

Libby, who did not participate in the study, said the work was valuable for 
identifying the CB2 receptor as a potential target for treatment in 
hardening of the arteries, and showing that a natural substance could help.

But he noted that controlling one's weight, exercising and eating right 
have already been proven to reduce a person's risk of heart attacks and 
strokes from clogged arteries.

Dr.  Edward A.  Fisher of the New York University School of Medicine said 
THC's impact on artery-clogging in the experiment was relatively modest, 
and that it's not clear that results would apply to people.
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MAP posted-by: Jay Bergstrom