Straight Dope on the Munchies

By Kristen Philipkoski
Source: Wired Magazine

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."

Source: Wired Magazine (CA)
Author: Kristen Philipkoski
Published: April 11, 2001
Copyright: 2001 Wired Digital Inc.
Contact: newsfeedback@wired.com
Website: http://www.wired.com/

Related Article & Web Sites:

Journal Nature http://www.nature.com/nature/

National Institute of Alcohol Abuse and Alcoholism http://www.niaaa.nih.gov/