Body's Pot-Like Chemicals May Help Curb Pain
Targeting These Compounds May Benefit Chronic Pain Conditions
June 22, 2005 --The body makes compounds that work like marijuana to
suppress pain, a new study in the journal Nature shows.
"This study shows for the first time that natural marijuana-like
chemicals in the brain have a link to pain suppression," says researcher
Daniele Piomelli, PhD, in a news release.
Those chemicals are called cannabinoids. They act like those in marijuana,
says Piomelli. He is a pharmacology professor and director to the Center for
Drug Discovery at the University of California at Irvine's medical school.
The study was based on rats, not people. However, the findings may lead to
new pain treatments, says Piomelli. "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," he says.
Putting Pain on Hold
Pain doesn't always register right away. It can briefly be buffered, say
Piomelli and colleagues.
That phenomenon, called stress-induced analgesia, was the focus of their
experiment. In stress-induced analgesia, a sudden injury activates certain
brain pathways, temporarily suppressing pain, say the researchers.
Their tests showed a rapid rise in the levels of a cannabinoid called 2-AG
in male rats' brains after injury.
But 2-AG doesn't hold off pain forever. Ordinarily, it subsides after a
short time, ushered away by an enzyme also made by the body.
The study targeted that enzyme, called monoacylglycerol lipase (MGL). With
MGL sidelined, 2-AG stayed in the brain for longer than normal. Under those
circumstances, stress-induced analgesia increased. In other words, pain stayed
at bay longer.
MGL may be a previously unrecognized therapeutic target, write
"There is no prescription or over-the-counter drug that allows us to
manipulate the level of the brain's marijuana-like compounds," says
researcher Andrea Hohmann, PhD, in a news release.
A drug based on the new research would likely be more effective and specific
than smoked marijuana, says Hohmann. She is a neuroscientist in the University
of Georgia's psychology department who also worked on the experiment.
The chemical used to inhibit MGL in the study was developed by Piomelli's
group. It has been patented by the University of California at Irvine and the
Italian universities of Urbino and Parma, according to the news release.