See
Report On Medical
Value Of Marijuana Published In Sacramento Paper Where It Can Be Ignored By Wilson &
Lungren(Ed. note:
These two articles from leading British scientific journals add a little to the
explanation of the research, but perhaps they add even more to the understanding of how
tragic have been the delays in research on medical marijuana. There is so much that we
should have – could have – already discovered, if the party line of marijuana
prohibition had not been threatened by the truth. Both of these distinguished journals
have already called for the legalization of marijuana.)
See
The New
Scientist Drops Its Bombshell – The UK Disaster for Prohibitionists Gets Even
Worse. Introduction
and
The Lancet Editorial "The smoking of cannabis, even long term, is not harmful to health."
The New Scientist
letters@newscientist.com
http://www.newscientist.com/
September 26, 1998
By Jonathan Knight
EASING THE AGONY
Marijuana Does More Than Merely Make You Stoned
PEOPLE who smoke cannabis believe that it eases pain, but its analgesic powers have
been little studied. Now researchers in the US have found that the active ingredient in
marijuana, THC, targets the same pain centres in the brain as morphine.
The ability of marijuana to soothe has been hard to fathom from animal studies.
Scientists often test the power of painkillers by timing how long it takes a drugged rat
to flick its tail away from a hot lamp, but since cannabis slows down motor neurons, rats
given cannabis may just be too high to react quickly.
To tease apart these two neural pathways, Ian Meng and his colleagues at the University
of California Medical Center in San Francisco analysed THC’s effect on a specific
pain centre in the brain, the rostral ventromedial medulla or RVM. The RVM can amplify or
block pain signals travelling from the spinal cord to the brain, and opioids such as
morphine activate painblocking cells in the RVM.
The researchers took rats and inserted a tube through their skulls and into the RVM.
After recovering from the surgery, the rats received an intravenous injection of a THClike
substance. As expected, they were much slower to flick their tails away from a hot lamp.
Meng then showed that he could restore the rats’ heat sensitivity by shutting down
the RVM with a neural inhibitor injected through the skull tube (Nature, vol 395, p 381).
To prove that inactivating the RVM did not just restore motor coordination, Meng placed
drugged rats on a "rotor rod" which rotates under their feet like a log in a
river. "Give them a cannabis drug and they just fall right off," he says. They
continued to do so even after the RVM was inactivated.
"This is very important work," says Daniele Piomelli, a
neurologist at the University of California’s Irvine campus. "If medical
scientists start to look with greater interest at cannabis as a result, that’s a
major achievement."
From the Lancet
lancet.editorial@elsevier.co.uk
http://www.thelancet.com/
September 26, 1998
By Paul M Rowe
CANNABINOID ANALGESIA EXPLAINED
Marijuana, it is claimed, relieves pain, but how? In a new study, the analgesic effect
of cannabinoids has been found to work via a part of the brain stem also used by opioids. But, marijuana’s activity is pharmacologically dissociable from that
of opioids (Nature 1998; 395:381-83)
Researchers in Howard Fields’ laboratory at the University of California, San
Francisco (CA, USA) gave rats a cannabinoid and then tested their pain threshold with the
tail-flick test—ie, how fast the rats moved their tails away from a heat lamp.
Inactivation of the rostral ventromedial medulla (RVM) by microinjection of muscimol,
which mimics an inhibitory neurotransmitter, prevented the analgesia caused by the
cannabinoid.
The activities of single neurons in the RVM were correlated with the changes in pain
thresholds caused by intravenous administration of opioid and cannabinoid agonists and
antagonists. For example, the cannabinoid antagonist SR141716A alone induced hyperalgesia,
indicating that endogenous cannabinoids modulate pain thresholds.
"The RVM projects directly to the spinal cord, and is the final common pathway for
a lot of pain-modulating brain regions that feed into it. When you administer
cannabinoids, and record from neurons in the RVM, you see a difference in firing
correlated with the longer latency in the tail-flick test. Then, when we injected the
morphine antagonist naloxone after the cannabinoid, it did nothing further to the
tail-flick test, and nothing further to the firing of cells in the RVM", says first
author Ian Meng.
It is unclear when and why the endogenous cannabinoid system is normally activated, but
cannabinoids alone are not effective for severe pain so they are "not going to
replace morphine", says Meng. However, he adds, "cannabinoids
increase appetite, and so may help alleviate the nausea caused by opioids."
Supported