A new study has found scientific evidence and further explanation for why cannabis increases and stimulates the appetite, more commonly known as “the munchies.”
The study, championed by researchers at Washington State University and published in the peer-reviewed journal Scientific Reports was performed by administering vaporized cannabis sativa to mice, after which they scanned their brains using technology similar to an MRI machine to see how the mice reacted.
According to a press release, the researchers found that a particular set of neural cells in the hypothalamus of the mice, an area of the brain most associated with maintaining homeostasis in the body, was activated in the mice who were exposed to cannabis. The same neural cells did not appear to become activated in the mice who were not exposed to the cannabis vapor.
“When the mice are given cannabis, neurons come on that typically are not active,” said Jon Davis, an assistant professor of neuroscience at WSU and corresponding author on the paper. “There is something important happening in the hypothalamus after vapor cannabis.”
Now, this is not the first study to associate cannabis use with hypothalamus stimulation. A 2015 study published in Nature found that activation of a certain cannabinoid receptor in the brain which in turn regulates a group of neurons that normally suppress appetite is believed to be what causes cannabis to increase hunger in its users. A 2019 study by UC Davis built on this knowledge by introducing vaporized cannabis as opposed to injected, as was used by most cannabis-related studies before it. The most recent study at Washington State University attempted to build on that knowledge in a bit of a different way.
The exact methods used by Davis and the Washington State University researchers were described in Scientific Reports using the following language:
“To determine how cannabis vapor affects temporal feeding patterns, we housed rats in metabolic chambers with real-time automated feeding measurement of meal frequency and meal size following exposure to air or a behaviorally characterized dose of cannabis vapor known to elicit feeding behavior,” the study said. “Further analysis of meal patterns revealed that cannabis vapor exposure promoted increased meal frequency and reduced meal size throughout the evaluation period, suggesting that inhaled cannabis may provoke motivational components of feeding.”
Beyond the more-or-less direct association that inhaling cannabis vapor tends to increase appetite, the research team involved in this study took it a step further. They used what’s known as a “chemogenetic” technique, which according to the National Library of Medicine is “technique that allows for the reversible remote control of cell populations and neural circuitry via systemic injection or microinfusion of an activating ligand.” This is a very scientific and fancy way of saying that certain groups of cells can be turned on and off like a “light switch” as Washington State University described it.
This light switch technique was used to essentially block the effects of cannabis from the group of neurons that were lit up in the mice, scientifically known as Agouti Related Peptide (AgRP) neurons. Essentially, what they found was that cannabis increased appetite in mice who did not have these neurons turned off and had no effect on appetite when the neurons were blocked.
The researchers also found that cannabis managed to stimulate appetite in the mice without inhibiting their ability to move around, referred to as “locomotor activity.”
“Our data demonstrate that inhalation of cannabis vapor augments the appetitive phases of feeding behavior as evidenced by an increase in the number of meals consumed, a decrease in meal size and enhanced effort-based responding for palatable food,” the study said. “Notably, these behavioral observations occurred in the absence of reduced locomotor activity, and in the presence of increased energy expenditure.”
If all of that scientific jargon didn’t really make sense to you, Davis best summarized the findings of this study in the following, very succinct statement:
“We now know one of the ways that the brain responds to recreational-type cannabis to promote appetite,” Davis said.