COMMENT

Cannabis campaign It's official dope can ease your pain

Drugs derived from marijuana may reduce the plight of cancer and Aids
sufferers.
By Tim Cornwell

New research in the United States has confirmed for the first time that
drugs derived from the active ingredients in marijuana are an effective
pain reliever. Studies at three major US universities show these
"cannabinoids" dampen pain via the same mechanisms as morphine and other
opiates.

The findings may be an argument for developing synthetic compounds rather
than saying "smoke pot for pain", said one researcher. But they also
suggest that people smoking marijuana for medical reasons are "experiencing
pain relief", not just enjoying a high, he said. Marijuana's role in easing
pain was a key issue in California's hotly contested vote last year to
allow doctors to recommend it for patients such as cancer or Aids sufferers.

Supporters claim it relieves the symptoms of pain and nausea without the
addictive sideeffects of opiates. The new studies will only add fuel to
the controversy, at a time when some opponents of medical marijuana in the
US have grudgingly conceded that there should at least be studies of its
possible effects. Some results suggested that cannabinoids may relieve the
symptoms both of arthritis and hyperalgesia, extreme sensitivity to pain
linked to nerve diseases and spinal cord injuries. Researchers from the
University of California at San Francisco, from Brown University and the
University of Michigan, reported their findings at a meeting of the Society
for Neuroscience in New Orleans. They were based on animal studies using
THC, the active ingredient in marijuana, and a synthetic cannabinoid, WIN
55212.

The studies showed that "substances similar to or derived from marijuana,
known as cannabinoids, could benefit the more than 97 million Americans who
experience some form of pain every year," the Society of Neuroscience said
in a press release. They have a "direct effect on pain signals in the
central nervous system and peripheral tissues," and "could be manipulated
to form a new type of pain reliever".

At San Francisco, the research included measuring pain suppression in rats
by seeing how long it took them to remove their tails from an
"uncomfortable heat source". Injections of less than a tenth of a millionth
of an ounce caused a profound loss of pain sensitivity. At the University
of Michigan, similar experiments were conducted on three rhesus monkeys,
confirming that after a dose of cannabinoids they were slower to remove
their tails from a tub of water kept at 50 degrees Celsius. But along with
these simple observations, researchers also monitored the biochemical
reactions involved. The research suggests cannabinoids can, like morphine,
reduce pain in two different ways, said Dr Barton Manning of UC San
Francisco.

Firstly, they can directly suppress neurons in the peripheral and central
nervous system that convey pain information from the body to the brain.

But they can also "talk" to paintransmission neurons in the spinal cord
and influence the number of pain signals that are allowed to reach the
brain.