Brain's Marijuana-like Chemicals Postpone Pain
Manipulating endocannabinoids may bring new, better analgesics
WEDNESDAY, June 22 (HealthDay News) -- Experts have long known that the brain has the ability to suspend the pain response in times of injury and great stress, even after traumatic incidents such as gunshot wounds.
Now, a new study in rats suggests marijuana-like neurochemicals called endocannabinoids may be key to this process.
The discovery may lead to a new class of painkillers with fewer side effects than existing pain medications, report researchers at the University of California, Irvine (UCI). Their study appears in the June 23 issue of Nature.
"This study shows for the first time that natural marijuana-like chemicals in the brain have a link to pain suppression," researcher Daniele Piomelli, a professor of pharmacology and director of the Center for Drug Discovery at the UCI School of Medicine, said in a prepared statement.
Stress can provide a delayed pain reaction in certain situations, an effect called stress-induced analgesia. Previous research has identified two kinds of stress-induced analgesia mechanisms in the body -- opioid and non-opioid. This study is the first to offer evidence that the non-opioid form is produced by cannabinoid compounds.
"If we design chemicals that can tweak the levels of these cannabinoid compounds in the brain, we might be able to boost their normal effects," Piomeilli explained.
"Aside 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," he added.
More information
The National Pain Foundation has advice on dealing with pain.
-- Robert Preidt
SOURCE: University of California, Irvine, news release, June 22, 2005
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Body's own 'cannabis' helps pain
A cannabis-like chemical produced naturally in the brain aids pain relief, researchers have found.
The US scientists said 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, writing in Nature, the team said their new understanding of how the brain chemical works could lead to drugs with fewer side-effects.
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 - a response called stress-induced analgesia.
A study in rats by the researchers from the University of California, Irvine, and the University of Georgia found, for the first time, how chemicals called endocannabinoids play a part in this process.
Production of one cannabinoid compound, 2-AG, was found to be triggered by stress-related pain.
The researchers then looked at ways of boosting this natural response.
Normally, an enzyme called monoacylglycerol lipase brings the production of 2-AG to a halt.
The team, including Professor Danielle Piomelli, director of the Center for Drug Discovery at the University of California, Irvine, 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 said: "This study shows for the first time that natural marijuana-like chemicals in the brain have a link to pain suppression.
"Aside 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.
"If we design chemicals that can tweak the levels of these cannabinoid compounds in the brain, we might be able to boost their normal effects," Professor Piomelli said.
Dr Andrea Hohmann, a neuroscientist at the University of Georgia, who also worked on the research, added: "There is no prescription or over-the-counter drug that allows us to manipulate the level of the brain's compounds.
"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, told the BBC News website said the paper added to knowledge about how the body dealt with pain.
"This 2-AG cannabinoid doesn't have a receptor in the brain.
"So while it was known it played a role in the body's response to pain, people did not know how."
Source: BBC News Online, 22/06/2005