Researchers at Washington State University (WSU) say they have identified key neurons in the brain that are behind an appetite-inducing phenomenon familiar to cannabis users called the munchies.
Previous research found a link between cannabis use and increased activity in the hypothalamus, which, among other things, regulates appetite. The new research study takes those studies even further by identifying typically dormant appetite-increasing neurons within the same brain region, which become activated after cannabis use.
The researchers behind the finding believe their work can not only aid sufferers of anorexia and other eating disorders, but may also pave the way toward a treatment that allows regular cannabis users to ‘turn off’ this often unwanted side effect.
Cannabis Use and the Munchies Meets Science
“It is well established that cannabis use promotes appetite,” researchers wrote in 2019. “However, how cannabis interacts with the brain’s appetite center, the hypothalamus, to stimulate feeding behavior is unknown.”
In that study, the research team was able to firmly establish that vaping cannabis caused the stimulation of the hypothalamus in rat brains, firmly establishing a link between anecdotal evidence for weed munchies and the scientific method.
“We found that vapor cannabis exposure promoted food intake in free-feeding and behaviorally sated rats, validating the appetite-stimulating properties of cannabis,” they explained at the time. Still, the exact neurons and pathways responsible for the munchies remained unidentified.
Now, those same researchers have published a new study. According to their latest experiments, they have drilled down to the exact neural pathways behind this phenomenon, opening up the door for potential therapies targeting appetite-related medical conditions.
Rats Who Vape Cannabis Reveal Secrets of Weed-Induced Appetite Increase
In this latest study, published in the journal Scientific Reports, WSU assistant professor of neuroscience Jon Davis and his associates exposed laboratory mice to vaporized cannabis sativa. Experiments with cannabis often involve directly injecting mice with THC, the active ingredient in cannabis. However, Davis’ team decided to intoxicate the mice using cannabis vapor to better simulate how recreational human users often consume cannabis.
The mice were observed using calcium imaging technology that works similarly to a brain MRI to track how the vaporized cannabis affected the activity of neurons within the hypothalamus. According to the press release announcing their findings, when the mice “anticipated and consumed palatable food,” the cannabis activated particular neurons that were not activated in unexposed mice.
“When the mice are given cannabis, neurons come on that typically are not active,” Davis explained. “There is something important happening in the hypothalamus after vapor cannabis.”
The researchers also found that a well-known cannabis target called the cannabinoid-1 receptor controls the activity of a set of well-known “feeding” cells in the hypothalamus called Agouti Related Protein neurons.
Using this information, they were able to use a “chemogenetic” technique that operates like a chemical light switch to turn the affected appetite-inducing neurons on and off. As expected, when the neurons were turned off, the increased appetite of the lab mice disappeared. The researchers say they have a much clearer picture of a key mechanism behind cannabis-induced munchies.
“We now know one of the ways that the brain responds to recreational-type cannabis to promote appetite,” said Davis.
Creating Treatments to Turn the Munchies On and Off
While the study is the first of its kind to track down the specific neurons associated with increased appetite due to vaporized cannabis, it could help scientists find ways to activate these cells without the intoxicating effects of cannabis use.
This type of therapy could be particularly useful to people who use cannabis during chemotherapy or other treatments that often result in severe weight loss but would prefer to avoid getting “high” at the same time. This research could also result in treatments for regular cannabis users who are seeking the plant’s intoxicating effects but don’t want to experience the associated increase in appetite.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.