Source: Science News Contact: scinews@sciserv.org Website: http://www.sciencenews.org/ URL: http://www.sciencenews.org/sn_arc98/7_11_98/fob2.htm Pubdate: 11 Jul 1998 Author: J. Brainard

MARIJUANA CHEMICAL TAPPED TO FIGHT STROKES

The breakfast table may someday feature not only orange juice and vitamins but also a more exotic health booster-a compound extracted from marijuana.

Cannabis contains a chemical that can protect cells by acting as an antioxidant, a new study shows. More effective than vitamins C or E, it offers an appealing option for the treatment and perhaps prevention of stroke, neurodegenerative diseases, and heart attacks, the researchers suggest.

However, there's no worry that those who take it will become too stoned to read the morning paper. The compound, called cannabidiol, doesn't make people high.

Scientists have yet to test whether the chemical has a protective effect in people. In test-tube experiments, researchers at the National Institutes of Health (NIH) in Bethesda, Md., exposed rat nerve cells to a toxin that is typically released during strokes. Cannabidiol reduces the extent of damage, the scientists report in the July 7 Proceedings of the National Academy of Sciences.

In follow-up studies, the researchers induced strokes in rats and treated them with cannabidiol. Those experiments are not yet complete, but "we're getting some good results," says Aidan J. Hampson, an europharmacologist at NIH.

Researchers suspect that many antioxidants can reduce the severity of ischemic strokes, in which blood vessels in the brain become blocked. During ischemic strokes, which make up 80 percent of all strokes, a toxin initiates the release of reactive oxygen molecules called free radicals into the bloodstream. These harmful molecules are under suspicion as one of the agents that cause stroke damage, such as paralysis and loss of speech and vision. Antioxidants such as cannabidiol neutralize free radicals and so might limit the damage.

The NIH researchers had suspected that the group of molecules including tetrahydrocannabinol (THC), the marijuana ingredient that produces a high, would act as antioxidants. In their study, THC and cannabidiol provided equal defense against cell damage. An earlier study at the University of Arizona in Tucson turned up no side effects of cannabidiol in people given large doses.

A pharmaceutical company, Pharmos in Rehovot, Israel, is already conducting human clinical trials using a synthetic marijuana derivative, Dexanabinol, to treat damage from strokes and brain injury. Like cannabidiol, this compound is an antioxidant and does not produce euphoria.

"This is a promising area [of research] . . . particularly because we have so few effective means of treating stroke," said JoAnn E. Manson, a researcher in preventive medicine at Harvard Medical School. Stroke is the third leading killer in the United States (SN: 12/21&28/96, p. 388).

The NIH researchers don't anticipate using cannabidiol to treat hemorrhagic stroke, characterized by bleeding within the brain, Hampson says. Antioxidants, however, could help treat other diseases that appear to be caused in part by free radicals. These include heart disease and two neurodegenerative disorders, Alzheimer's disease and Parkinson's disease.

References:

Hampson, A.J., et al. 1998. Cannabidiol and tetrahydrocannabinol are neuroprotective antioxidants. Proceedings of the National Academy of Sciences 95(July 7):8268.