The uncontrollable urge to eat often experienced after one smokes marijuana, or "the munchies," is most likely caused by a reduction of activity in brain nerves linked to appetite suppression.
A team of researchers monitored brain circuitry that promotes eating by manipulating the cellular pathway that regulates marijuana's effect on the brain using transgenic mice, Yale University reported. The study allowed the researchers to observe how the appetite section of the brain responds to marijuana and influences hunger by reversing the appetite-suppressing mechanism.
"It's like pressing a car's brakes and accelerating instead. 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" said lead author Tamas Horvath.
It is not news that cannabis use can increase one's appetite, and researchers have also long-known activating the cannabinoid receptor 1 (CB1R) can lead to overeating. Nerve cells called pro-opiomelanocortin (POMC) neurons are believed to be the primary target of reducing behaviors such as eating when full.
"This event is key to cannabinoid-receptor-driven eating," Horvath said. "More research is needed to validate the findings." Whether this primitive mechanism is also key to getting "high" on cannabis is another question the Horvath lab is aiming to address.
The findings could also have implications for cancer patients, who often lose their appetite as a result of harsh treatments.
The researcher was published in a recent edition of the journal Nature and was funded by the National Institutes of Health.
