A team of scientists believe they have finally discovered why marijuana causes increased appetite and cravings for food, otherwise known as “the munchies”. Researchers at Washington State University published a study this week in the journal Nature, pinpointing specific neurons in the hypothalamus that are activated by cannabis which spark hunger.
How Marijuana Affects Appetite
The munchies have been anecdotally associated with marijuana use for centuries, but the biological mechanisms behind this phenomenon have remained a mystery. This new research provides an explanation grounded in neuroscience.
Dr. Marco Koch, lead author on the study, said “These neurons are responsive to qualities of food like taste and palatability, but they also regulate appetite independent of food. What we found is that phytocannabinoids [in marijuana] selectively activate these brain cells, essentially tricking the brain into thinking you are starving.”
The researchers identified a subpopulation of about 5,000 appetite-stimulating neurons, located in a brain region called the arcuate nucleus of the hypothalamus, that contain a large number of CB1 receptors. THC and other cannabinoids in marijuana can bind to these CB1 receptors and directly activate the neurons.
Experiments on Mice
The WSU team performed a series of experiments on mice to reach these conclusions. They used advanced genetic techniques to mark the specific appetite-promoting neurons with a fluorescent protein, allowing them to visually track the cells’ activity.
They found that exposing mice to a cannabinoid caused these arcuate nucleus neurons to rapidly increase firing, indicating the cells were activating. Additionally, even when the neurons were artificially silenced, the cannabinoids had no impact on food consumption, confirming that the specific neuronal subpopulation is essential for the effects of marijuana.
| Type of Mouse Model | Impact of Marijuana Chemicals |
|---|---|
| Normal mice | Increased firing of appetite neurons and eating behavior |
| Mice with silenced appetite neurons | No change in eating behavior from marijuana chemicals |
Evolutionary Explanation
The researchers believe endocannabinoids, natural hunger-regulating chemicals in the body similar to compounds found in cannabis, may normally act on these CB1 receptors to drive us to seek out food when energy levels are low.
Dr. Koch speculated “THC appears to tap into this physiological control circuit, mimicking the effects of endocannabinoids to hijack appetite regulation.” Marijuana chemicals may exploit this biological pathway designed to motivate eating when needed, causing the intense desire for snacks well beyond metabolic requirements that underlies the quintessential “munchies”.
Implications of Findings
These revelations around marijuana and neurons controlling hunger have wide-ranging implications. Explaining the mechanism of action provides biological validation for the age-old cultural phenomenon of increased appetite from cannabis.
On a clinical level, scientists hope that by targeting this specific neural population they can develop treatments for eating disorders or other appetite-related conditions. At the same time, the addiction potential of marijuana may also be closely tied to effects on this hunger pathway.
Additionally, understanding neurobiological links between cannabinoids and feeding behavior may lead to the development of new drugs based on marijuana chemicals to help manage nutrition in elderly, sick, or impoverished populations. However, more research is still required to explore potential medical applications targeting this system.
For now, the WSU team’s findings definitively show that marijuana works directly in the brain through CB1 receptors on arcuate nucleus neurons to cause the munchies. So next time you smoke up and raid your kitchen for snacks, you’ll know it’s because your hypothalamus is telling you you’re starving!
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