Naturally produced 'cannabis' in the brain helps with pain relief

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News-Medical.Net Thursday, 23-Jun-2005 Medical Research News

Naturally produced 'cannabis' in the brain helps with pain relief

Researchers in the United States have found that a cannabis like

chemical produced naturally in the brain helps with pain relief.

They say the finding may lead to new drugs which can stimulate this

natural response.

Research has so far concentrated on developing compounds in cannabis

itself into medications, but this study shows for the first time that

natural marijuana-like chemicals in the brain have a link to pain

suppression.

The US scientists say their new understanding of how the brain

chemical works could lead to drugs with fewer side-effects.

Professor le Piomelli, director of the Center for Drug

Discovery at the University of California, Irvine, says that when the

body experiences pain under stressful circumstances, such as an

injury during sport or even after a gunshot wound, the body is

protected for a period of time.

This response is called stress-induced analgesia.

In a study in rats the team found, for the first time, how chemicals

called endocannabinoids play a part in this process.

The production of one cannabinoid compound, 2-AG, was found to be

triggered by stress-related pain, so the researchers then looked at

ways of boosting this natural response.

As an enzyme called monoacylglycerol lipase normally brings the

production of 2-AG to a halt, the team, developed a chemical which

was able to block the enzyme's action, meaning the body could

theoretically continue to keep producing 2-AG.

Professor Piomelli says the study shows for the first time that

natural marijuana-like chemicals in the brain have a link to pain

suppression, and apart from identifying an important function of

these compounds, it provides a template for a new class of pain

medications that can possibly replace others shown to have acute side

effects.

Piomelli says if chemicals can be designed that can tweak the levels

of these cannabinoid compounds in the brain, it might be possible to

boost their normal effects.

Dr Hohmann, a neuroscientist at the University of Georgia, who

also worked on the research, says as yet there is no prescription or

over-the-counter drug that allows us to manipulate the level of the

brain's compounds.

She says this is the first time anyone has shown that one of the

body's natural occurring cannabinoids, 2-AG, has anything to do with

pain regulation under natural conditions.

Dr Anita Holdcroft, a reader in anaesthesia at Imperial College, says

the study adds to knowledge about how the body deals with pain.

The study is published in the current edition of Nature.