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Scientists sniff out why marijuana smokers get the "munchies"

Scientists may have discovered the secret behind why some stoners feel the urge to snack.


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 A mouse study has shown that the brain receptors for cannabinoids, the active ingredients in marijuana, also are in charge of the brain’s pathway to the olfactory bulb. That area is responsible for sending smells that your nose picks up to the part of the brain that interprets the odor.

The researchers showed that when mice were given the cannabinoid tetrahydrocannabinol (THC), the animals wanted to eat more. However, genetically-modified mice with only a few cannabinoid receptors were not as affected by the presence of THC.

The scientists explained when the mice felt hungry, the cannabinoid receptors were activated. That in turn made the olfactory circuit work in overtime, meaning everything smelled even better. Fewer sensors meant less of an effect.


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  “The ‘munchies’ effect of marijuana depends on cannabinoid receptors. The number and the activity of these receptors can determine their effects,” study author Giovanni Marsicano told the National Post. “Our paper suggests that the impact of marijuana on olfaction (human beings' sense of smell) might be determinant for its effect on food intake.”

Smithsonian Magazine points out that the body itself can naturally produce some cannabinoids, but THC is a plant-derived form that can cause other effects. THC works with the body’s endocannabinoid system, which affects emotion, memory, pain control and appetite.

THC likely developed in marijuana plants as an evolutionary mechanism to deter plant-eating creatures from snacking on the plant by making them feel high.

The researchers hope that the findings mean that olfactory system can be changed in obese or anorexic patients as a means to regulate their appetite.

“Many feeding disorders are accompanied by altered perception in general. For instance anorectic people see themselves as fat,” Marsicano said. “Smell is particularly linked to food intake and is particularly altered in different diseases. Obese people tend to be more attracted by food odours Smell and its regulation by the (endo)cannabinoid system could represent a future target for therapies against these and other diseases.”

The study was published on Feb. 9 in Nature Neuroscience.