Marijuana Compound Fights Hardened Artieries
April 6, 2005 -- The active ingredient in marijuana that produces changes in brain messages appears to fight atherosclerosis -- a hardening of the arteries.
But puffing pot probably won't help. The findings, reported in the journal Nature, "should not be taken to mean that smoking marijuana is beneficial for the heart," says Michael Roth, MD, a professor of medicine at UCLA medical school.
It takes a very specific amount of THC -- marijuana's key chemical -- to help the arteries. That dose is too low to produce mood-altering effects in the brain, according to the new study.
"It would be difficult to achieve such specific concentrations in the blood by smoking marijuana," Roth explains in a Nature editorial.
Smoking Pot: Bad for the Heart?
Smoking marijuana can speed up the pulse and raise blood pressure (followed by a sudden fall upon standing or walking), Roth notes.
"These effects lower the exercise threshold for chest pain [angina], and are an independent risk factor for heart attack and stroke," he writes. Inhaling marijuana smoke can also impair oxygen delivery via the blood, says Roth.
The best way to take advantage of THC's artery-protecting effects may be by developing new prescription drugs "rather than using marijuana or oral THC as medicines," he writes.
Testing THC on Mice
The new study was conducted on mice, not people. First, mice went on an 11-week fatty diet designed to clog their arteries. For the last six weeks of the diet, some mice also got an orally administered low dose of THC along with the high-fat food.
Afterward, the mice who had received THC had fewer signs of atherosclerosis. None of those mice died during treatment or showed unhealthy behavior, says the study.
The results may be due to THC's anti-inflammatory properties, write the researchers, who included François Mach, MD, of the cardiology division at University Hospital in Geneva, Switzerland. Inflammation has been shown to be associated with the development of atherosclerosis.
Tracing THC's Effects
The researchers took a closer look at THC. They knew the chemical has two receptors, called CB1 (mainly found in the brain) and CB2 (mostly found outside the brain).
When they used another drug to block CB2 receptors in the mice, THC couldn't protect the animals' arteries. As for the CB1 receptors, the THC dose used in the study was too low to affect them, so no "high" was created.
The study and editorial appear in Nature's April 7 edition.
LONDON (Reuters) - An active ingredient in cannabis can ease inflammation and slow the progression of coronary artery disease in mice, and possibly humans, researchers said on Wednesday.
Daily low doses of the ingredient, THC, prevented atherosclerosis, a primary cause of heart disease and stroke in western countries, without producing the associated high.
"We have proven that very low doses of cannabis therapy will have an anti-inflammatory effect that will slow the progression of atherosclerosis in mice," said Dr Francois Mach, of Geneva University Hospital in Switzerland.
He and his team do not know whether TCH, or delta-9-tetrahydrocannabinol, will have the same effect in humans. But they believe the discovery will help find compounds that produce the same effect in humans without side effects such as raised blood pressure or euphoria.
"The goal now is to find new molecules, new compounds, that will act only on this anti-inflammatory effect," Mach told Reuters. Atherosclerosis is a common disorder of the arteries. Fatty materials build up and eventually block the arteries and interfere with blood flow.
THC and similar molecules are known as cannabinoids. Cannabis, which contains more than 60 different cannabinoids, and hashish have been used for centuries for medicinal purposes.
Mach and his team gave mice which were genetically engineered to be prone to atherosclerosis very low oral doses of THC with food each day. The dose was about 10 times less than that from smoking cannabis.
"It is the first study showing any beneficial effect of cannabis therapy on atherosclerosis," said Mach.
Cannabis creates a high when it binds to receptors called CB1 on the surface of cells in the brain. In the mouse study, another receptor, CB2, which is found on immune system cells and has nothing to do with euphoria, was affected. The dose given to the mice was too low to create a sense of euphoria.
Mice given THC had a slower progression of the disease than other mice not given the compound. The scientists are now studying whether THC can prevent the illness in the rodents.
"We are planning to look in more detail into how cannabis interferes with inflammation," said Mach.
"What we have proven in mice is that acting on this receptor 2 ... has an anti-inflammatory effect that is very beneficial against the development of atherosclerosis."
In a commentary on the research in Nature magazine, Michael Roth, of the University of California in Los Angeles, described the findings as striking.
"But they should not be taken to mean that smoking marijuana is beneficial for the heart," he said.
On the contrary it increases the pulse rate and causes sharp rises and then falls in blood pressure upon standing and walking.
The Netherlands was the world's first country to make cannabis available as a prescription drug for cancer, HIV and multiple sclerosis (MS). In the United States it is used to treat weight loss in AIDS patients and nausea and vomiting in cancer sufferers.
In Britain, GW Pharmaceuticals Plc has been pioneering cannabis-based medicine.
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