Many marijuana users find a common thought, a common question in fact, right after taking up the drug: "Why am I so hungry?" So, researchers are investigating the different parts of the brain in order to find the root cause of ‘marijuana munchies’.  A group of neuroscientists reported that they have discovered a major clue underneath a cluster of neurons they think responsible for making the marijuana users feel full.

The cluster of neurons called the POMC is located in the hypothalamus, which is a region of the brain. Scientists typically associate the hypothalamus with base instincts like alertness, arousal, and feeding. Yale School of Medicine neuroscientist and the team leader, Tamas Horvath said that POMC neurons generally work by sending a chemical signal to tell the brain it’s sated, so stop eating.

Previously, neuroscientists tried to shut down the mice’s POMC neurons, and all of them turned out to be morbidly obese. The team figured out the exact opposite, when it comes to marijuana, saying that cannabinoids should bind the neurons’ activity and make them fire less. This will halt the impulse to feed absurdly. The team also found out that after injecting cannabinoids to the mice, the drug seemed to turn off adjacent cells, which normally commanded the POMC neurons to slow down, resulting to increased activity. Simultaneously, the cannabinoids tend to activate a receptor in the POMC, causing the cell to switch into making endorphins, which are neurotransmitters that increase appetite.

When combined, the two effects create a ‘hungry effect’, even after dinner and smoking marijuana. Horvath said the neurons become drivers of hunger, adding that the weed turns into a gas pedal towards hunger.

Rockefeller University’s neuroscientists, Sarah Leibowitz and Jessica Barson said the study was innovative. Leibowitz explained that the study revealed an important, general driver of overeating. Barson said that Horvath’s team completed some excellent experiments.

One limitation of the study, however, is that it was employed in mouse brains, instead of humans’. Horvath reiterated that the hypothalamus had been a brain’s ancient part, which has evolved before animals, insisting that how such neural circuits work in the mice is similar in humans.

The study is not the final missing puzzle of the marijuana munchies as there are lots of neural processes layered in the hypothalamus, and cannabinoids might also affect the other regions of the brain. There were also previous studies involving cannabinoids and mice, indicating different findings. Horvath added that the munchies were possibly the sum result of cannabinoid effects in the brain as general.