Blame pot munchies on nerve cells that normally nix appetite

Potheads can blame their munchies on nerve cells that are supposed to keep them feeling full, scientists report February 18 in Nature.

“It’s like you’re driving your car downhill and you push your brakes, and all of a sudden the brake becomes the accelerator,” says coauthor Tamas Horvath, a neurobiologist at Yale University.

Horvath and his team gave mice a chemical that mimics the effects of marijuana by fastening to cannabinoid receptors, molecules in the brain that are involved in controlling appetite, feeling pain and other processes. The researchers then looked at the rodents’ brains to see what neural circuitry was active. To their surprise, nerve cells that normally suppress appetite lit up.

The team then experimented with turning those nerve cells, or neurons, on and off while the cannabinoid receptors were activated. Dampening the neurons’ activity made the mice less likely to munch, while stimulating the neurons encouraged the mice to eat more.

Marijuana changes which chemicals the fullness neurons release, the researchers found. The drug prompts nerve cells to make endorphins that serve as messengers to fuel hunger. The cells then unleash these endorphins instead of other compounds that signal fullness.

Hijacking neurons that normally suppress appetite may lead to treatments for people who have lost interest in food as a result of illness or medications, Horvath says.