STRAIGHT DOPE ON THE MUNCHIES

Most people, whether they use pot or not, know that the evil weed induces
what is affectionately known as "the munchies."

It's a mystery that scientists have been working to unravel over several
decades. Now, they've uncovered one more scientific point of the munchy
mechanism, which could lead to drugs that can help patients who need to
gain weight. Or lose it.

They've drawn the first firm link between "cannabinoids," and the body's
normal regulation of body weight. The study appears in the April 12 issue
of the scientific journal Nature.

"It has been known that cannabis can increase appetite," said George Kunos,
of the Virginia Commonwealth University, who led the research. "The novelty
here is evidence that the brain's own marijuana-like substances, or
endocannabinoids, are involved in the normal physiologic regulation of
appetite."

Marijuana-like molecules found naturally in the brain are called
endocannabinoids. In marijuana, they're called cannabinoids. The
researchers found that the function of these molecules in the brains of
mice is directly linked to a hormone called leptin, produced by body fat
that decreases appetite.

Mice were genetically engineered to lack cannabinoid function. After being
deprived of food, the genetically-altered mice ate less than normal mice.

The research into the activity of these molecules could eventually yield an
obesity drug, scientists say. In France, a company called Sanofi is working
on a weight-control drug that manipulates endocannabinoids.

It's well known that leptin keeps tabs on how much energy the body has, and
the researchers found that leptin also modifies the levels of endocannabinoids.

"When the fat or the energy stores go up, leptin reduces the
endocannabinoid levels. On fasting, the endocannabinoids go up and leptin
levels go down," said Raphael Mechoulam, an Israeli researcher at the
Hebrew University, who wrote a commentary accompanying the Nature study.

Also, the mice that had a defective leptin gene were obese, with high
endocannabinoid levels.

Will the study add credence to the safety of the medical uses of marijuana?
Kunos isn't so sure.

"This study does not allay concerns about the unwanted psychoactive side
effects of marijuana," said Kunos, who is now director of the National
Institute of Alcohol Abuse and Alcoholism. "However, it could raise the
possibility that drugs could be developed to potentiate the action of
endocannabinoids."

For example, drugs could be developed that block the enzyme that normally
degrades endocannabinoids in the brain.

"Since endocannabinoids are natural substances, such an approach may avoid
using a drug of abuse," Kunos said.

Nine states have decriminalized the use, possession and sale of marijuana
for medical purposes. But even with a prescription, patients can be
prosecuted under federal law. Some medical professionals are still
skeptical of legalizing marijuana.

"The plight of patients with HIV infection and advanced cancers is tragic,"
said Dr. Michael Miller, director of the Dane Country Medical Society in
Wisconsin in a recent testimony to the Assembly Committee on State Affairs.
"There is no scientific evidence that I am aware of that offering marijuana
cigarettes to these individuals equates to compassion."