Living with parasitic worms in your gut is not fun. Once they’ve gnawed and burrowed their way into your intestinal wall, they’ll sit there and feast on blood or steal nutrients from food, making you feel tired, sore, nauseous, and bloated.
But in mice at least, having worms might be a bit like eating cannabis edibles, according to research by a team of biomedical and parasite scientists from the University of California, Riverside.
By analyzing the chemical makeup of the worms living in a mouse host, scientists showed that the worms released endocannabinoids––the same chemicals found in weed but made by the body––and triggered the mouse gut to make them too.
They say these chemicals give the mice a “natural, localized high” and may allow the worms to go unnoticed by dampening down pain and the mouse’s immune system.
The scientists tested one particular worm, Nippostrongulus brasiliensisis, but found the same endocannabinoid coding genes in other parasitic worms––including those that infect humans.
Nicholas DiPatrizio, a physiologist specializing in the body’s endocannabinoid system, explained to me over Skype the difference between the worm “edibles” and edibles you might eat at your friend’s party. The chemicals in weed activate cannabinoid receptors throughout the body including the brain, producing feelings of euphoria, calm, or hunger.
The endocannabinoids the worms make activate the same receptors but only in the intestine and only for a short time, meaning they still have their pain-reducing and munchie effects but without the buzz. “We like to think of it as they’re produced on demand on the spot,” he said.
That the worms were making these chemicals was a surprise to the researchers, who initially thought there was something off with their data. Mice also make endocannabinoids as a way to fight infection and keep worm numbers down but the levels the scientists saw were 100 to 1,000 times higher than expected. They now think that by making their own endocannabinoids, the worms hijack a natural system in the mouse’s body for their own benefit.
The worm-made endocannabinoids may encourage mice to eat more, somewhat counteracting the effects of the worms stealing their food and draining their blood. Endocannabinoids also stimulate the production of other wound-healing and immune molecules, meaning the worms might be repairing some of the damage they cause.
Parasitologist Adler Dillman, who also worked on the study, told me that it’s in the best interests of parasites to keep their host healthy because they rely on the host to reproduce. “It’s not like the parasites are always interested in killing the host; they’re interested in having nice long co-associations so they don’t want to do a lot of damage,” he said.
Parasitic worm (helminth) immunologist Meera Nair, who initially formed the research team with DiPatrizio, thinks this newfound knowledge could be used to treat human ailments such as inflammatory bowel syndrome or celiac disease. Figuring out ways to make endocannabinoids at the site of inflammation could ease pain and repair damaged intestines—without the getting-baked side effects that could disrupt someone’s ability to work.
“We’ve stuck a piece of the puzzle in. It’s known that worms can be anti-inflammatory. We know that cannabis can be anti-inflammatory, manage pain and promote eating… We’re putting it all together,” she said.
Listen to our podcast about the world’s greatest mysteries that were solved by science.