Mouse Study Finds What Drives Marijuana Munchies

A new study from the Yale School of Medicine has found that the “munchies,” or that uncontrollable urge to eat after using marijuana, appear to be driven by neurons in the brain normally involved in suppressing appetite.

The researchers set out to monitor the brain circuitry that promotes eating by selectively manipulating the cellular pathway that mediates marijuana’s action on the brain, using transgenic mice.

“By observing how the appetite center of the brain responds to marijuana, we were able to see what drives the hunger brought about by cannabis and how that same mechanism that normally turns off feeding becomes a driver of eating,” said Tamas Horvath, lead author of the study.

“It’s like pressing a car’s brakes and accelerating instead,” said Horvath, a professor of neurobiology, obstetrics, gynecology, and reproductive sciences, and director of the Yale Program in Cell Signaling and Neurobiology of Metabolism.

“We were surprised to find that the neurons we thought were responsible for shutting down eating were suddenly being activated and promoting hunger, even when you are full. It fools the brain’s central feeding system.”

In addition to helping explain why you become extremely hungry when you shouldn’t be, the new findings could provide other benefits, like helping cancer patients who often lose their appetite during treatment, according to Horvath.

Researchers have long known that using cannabis is associated with increased appetite even when you are full. It is also well known that activating the cannabinoid receptor 1 (CB1R) can contribute to overeating. A group of nerve cells called pro-opiomelanocortin (POMC) neurons are considered as key drivers of reducing eating when full, the researchers explain.

“This event is key to cannabinoid-receptor-driven eating,” said Horvath, who points out that the feeding behavior driven by these neurons is just one mode of action that involves CB1R signaling. “More research is needed to validate the findings.”

Whether this primitive mechanism is also key to getting “high” on cannabis is another question the lab is aiming to address, Horvath added.

The study was published in the journal Nature.

Source: Yale University