Pubdate: Fri, 24 Jun 2005
Source: Red Deer Advocate (CN AB)
Copyright: 2005 Red Deer Advocate
Contact:  http://www.reddeeradvocate.com/
Details: http://www.mapinc.org/media/2492
Author: Lee Bowman

RESEARCH HOLDS HOPE FOR NEW CLASS OF PAINKILLERS

Researchers have found that marijuana-like chemicals in the brain 
help animals and people under extreme stress suppress pain and keep 
going despite a severe injury.

"This shows for the first time that natural marijuana-like chemicals 
in the brain have a link to pain suppression," said Daniele Piomelli, 
a professor of pharmacology at the University of California-Irvine 
and senior author of a study published recently in the journal Nature.

"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," said 
Piomelli, who also directs the Center for Drug Discovery at the 
university. In theory, the research done on rats suggests it is 
possible to design a pill that would have the same pain-relieving 
effects as smoked marijuana, but through an indirect mechanism that 
wouldn't carry the psychoactive side effects or legal perils of 
medical pot, the authors said.

The study has its roots in a phenomenon known as stress-induced 
analgesia. This is part of the body's primitive "fight or flight" 
survival kit that also makes our hearts race, our breathing quicken, 
reduces blood flow to some parts of the body and tightens our muscles 
as the parts of our brain that are key to sensing threats fire up to 
heightened awareness. Scientists have long known that a surge of 
stress hormones gives wounded soldiers, accident victims, injured 
athletes and others a short period of time in which the body's pain 
reaction is delayed and they can keep going to complete a task or reach safety.

Over time, researchers have determined that there are two types of 
stress-induced pain blockers, opioid and non-opioid, that work in 
both humans and most animals. The new study provides the first 
evidence that the non-opioid form is produced by marijuana-like 
(cannabinoid) compounds, although other research has shown they play 
a role in blocking pain.

Piomelli and lead author Andrea Hohmann, a neuroscientist at the 
University of Georgia, found one specific cannabinoid compound, 
called 2-AG, provides powerful and immediate response to the body's 
pain reactions during stress. And when they blocked 2-AG response in 
rats, they could only detect the opioid form of response to pain. 
Blocking receptors "where the marijuana acts virtually erased this 
form of stress analgesia," Hohmann said, leaving only the pathway 
that relies on opioids at work. Moreover, when they gave the rats a 
compound developed by Piomelli that blocks the breakdown of 2-AG, 
stress-induced pain relief increased dramatically.

Hohmann said a new drug that increased the body's own natural 
marijuana-like compounds might work something like the 
anti-depressant Prozac, which blocks the re-uptake of the 
brain-signaling compound serotonin, causing it to remain active longer.
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MAP posted-by: Beth