Can marijuana kill the pain without the high?

Scientists have found a way to decouple the psychoactive effects from the pain relief.
Written by Janet Fang, Contributor

The (unwanted) high that results from cannabis-based medications have limited their development as therapeutic painkillers. But a new study shows that modifying some of their chemical properties may minimize those side effects.

Marijuana is both analgesic (pain relieving) and psychoactive. And both of these effects are caused by its active component, known as tetrahydrocannabinol (THC).

So a team led by Li Zhang from the National Institute on Alcohol Abuse and Alcoholism wanted to find a way to utilize the chemical compounds in cannabis – which provides therapeutic relief for many things including cancer treatment side effects to muscle spasms from multiple sclerosis – but eliminate the unwanted motor impairment and psychosis.

In order to get high, THC binds to something called the cannabinoid type-1 receptor (CB1R) on cells. But to produce the other effect, previous research has shown that THC must bind to a different molecular target. (This is the part that was less clear.)

But now, the team discovered that THC relieves pain by binding instead to receptors for the brain-signaling compound known as glycine.

When THC binds to the glycine receptor (GlyR), that enables the development of a THC variant that only has analgesic properties.

To confirm that they can decouple marijuana’s pain-relief from its hallucinogenic effects, the team experimented on mice. If the glycine receptor is absent or if its activity is blocked by another drug, the mice experienced pain even when given THC, New Scientist explains.

"We found that this glycine receptor could be a primary target for developing non-psychoactive forms of cannabis," Zhang says.

The study appeared in Nature Chemical Biology yesterday.

Image: Cannabis sativa via Wiki

This post was originally published on Smartplanet.com

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