Most people are familiar with the munchies, the urge to stuff one’s face with (often junk) food brought on by marijuana use.

UC Riverside researchers have linked that same phenomenon with indulging in high-fat, high-sugar foods.

In essence, they have found that eating junk food stimulates some of the same cannabinoid receptors in the body that marijuana does, creating the urge to eat even more. And there appear to be almost no other factors involved.

If the cannabinoid receptors are blocked, the urge to overindulge disappears.

At least it does in lab mice. Evolutionary biologist Nicholas V. DiPatrizio said it’s unknown whether the mechanism works similarly in humans, but elevated levels of endocannabinoids (the chemicals that stimulate cannabinoid receptors) have been reported in obese humans.

DiPatrizio said the experiment, led by Ph.D. student Donovan Argueta, came out of studies examining the impacts of a high-fat Western diet on mice. A group of mice given that diet was observed to be overindulging in food.

“We said, ‘We see this behavior. What neurological responses are responsible for driving this?’” he said.

That question remains unanswered, but what the researchers did find was that the mice consuming the junk food diet had more than double the levels of endocannabinoids in their small intestines than the control mice. They also had the chemicals in their blood.

“This is a local event in the small intestine that also spills out into the blood and may affect the brain as well,” DiPatrizio said. “In the small intestine, there are nerves that connect the small intestine to the brain. We suspect (the endocannabinoids) modify the nerves in the brain.”

It’s not the same as smoking pot, he said. Cannabis, which binds to the same cannabinoid receptors, travels throughout the body when ingested and is not limited to the gut.

But the effect on appetite is similar.

What surprised DiPatrizio was how big a difference the diet made in the production of the endocannabinoids – “a doubling is a pretty large increase” – and how completely they were able to reverse the effect by administering a chemical that blocked the cannabinoid receptors.

“We used a drug called AM6545,” he said, a drug not yet available to consumers. “It clogs cannabinoid receptors outside of the brain. The brain also contains cannabinoid receptors that not only regulate feeding but also mood and other cognitive behaviors.”

AM6545 does not cross the blood/brain barrier. So it affected only the receptors in the intestines. But what it did there, DiPatrizio said, was remarkable.

Even though the mice still got fed the junk food diet, the appetites of the mice that received the drug returned to normal. He equated the change with a person being satisfied with eating a few potato chips instead of having the urge to consume the entire bag.

“A lot of times you get an effect (with a drug),” he said. “We were rather surprised that we completely normalized behavior. I think this speaks to the critical role of this mechanism.”

DiPatrizio, who has been studying the effects of cannabis and cannabinoids for years, said he and his team are currently working on identifying the way in which the receptors in the intestine connect with the brain to modify behavior.

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