NEW FRONTIER FOR MEDICAL CANNABIS -- TOPICAL POT

Anti-Inflammatory Traits Helped Heal Skin of Mice in Study

Skin allergies may be the next reason to use marijuana -- a topical
form, at least.

Scientists have long suspected that marijuana, used for recreational
purposes and to help fight chronic pain, nausea and even some mental
disorders like anxiety and depression, also had anti-inflammatory
effects in the body.

Now they think they know why.

In a study published in the current issue of the journal Science,
researchers show exactly how they think that works, elucidating how
the body's own cannabinoids, compounds that are similar to the ones
found in marijuana, reduce inflammation.

Mice had a harder time healing from wounds caused by ear tags used to
identify them when researchers blocked their internal cannabinoids,
said Dr. Meliha Karsak, lead author and scientist in molecular
neurobiology at the University of Bonn in Germany. Cannabinoids are
involved in many of the body's daily functions, scientists believe,
but they're still trying to figure out how.

Mice also healed faster from skin allergies with topical THC, the
main psychoactive ingredient in marijuana and other plants, she said.

Dr. Frank Lucido, a Berkeley physician who was not involved in the
study but regularly recommends medical marijuana, said the plant's
anti-inflammatory effects didn't surprise him. He has had patients
who say their psoriasis, an immune disease that affects the skin and
joints, and asthma get better when they smoke marijuana.

In the 1980s, scientists discovered receptors in the body that
respond to active compounds in cannabis, Karsak said. Once activated
with THC and other chemicals from marijuana, the receptors had
effects downstream, for instance changing a person's mood and
perception. Since then, two main receptors have been studied: One is
more prevalent in the central nervous system, the other in the periphery.

The one in the periphery seems to respond to cannabinoids in
inflammation and is found in cells of the immune system, said Dr.
Donald Abrams, a San Francisco General Hospital physician who has
studied the effects of marijuana use in HIV patients.

"Most people have believed for some time that the cannabinoid system
is involved in modulating the immune system," he said.

But experts say they're uncertain how such a controversial chemical
could reach the hands of patients with skin allergies. Scientists
would have to develop a product that had more effect on the
cannabinoid receptors in the periphery than in the brain and spinal
cord, where the psychotropic effects would be more common, said Dr.
Ben Cravatt, a researcher in the study and a professor in cell
biology at the Scripps Research Institute in La Jolla.

Karsak, however, said the experiments on mice showed that the dose of
THC in a topical cream for humans would be small enough to avoid
psychotropic effects. She also doubted that people could extract
enough THC from the cream for use as a recreational drug.

Contact with substances like poison oak can easily cause a
blistering, allergic skin reaction, said Dr. Stephen Katz, a
dermatologist and head of the National Institute of Arthritis and
Musculoskeletal and Skin Diseases. Topical steroids and other
medications work well against dermatitis, he said, adding that he
didn't think enough was known about cannabinoids and skin reactions
to create a medication from cannabinoids.

Dr. Mark Dahl, chairman of dermatology at the Mayo Clinic College of
Medicine in Arizona, cautioned patients against using marijuana for
their skin allergies. "I doubt that if they had a rash, rubbing their
marijuana plant would make much difference," he said.

California is the only state to allow physicians to recommend
marijuana for any medical purpose, unlike other states that dictate
its use in specific ailments, Lucido said.

Seventy-five percent of the patients Lucido treats with marijuana
complain of chronic pain. The rest have post-traumatic stress
disorder, depression, anxiety, headaches or muscle spasms, like in
patients with multiple sclerosis.

He said he hoped the study would convince politicians to invest in
more research about cannabinoids and help get more states to pass
medical marijuana laws.