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Microscopic worms also get the munchies from weed, study finds

When Oregon researchers studied Caenorhabditis elegans through genetic engineering, green implied the worm was reacting to cannabis. (Shawn Lockery)
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Shawn Lockery was wrapping up a week of studies on the food preferences of worms in 2016 when he decided to perform a fun Friday afternoon experiment.

Oregon had legalized recreational marijuana the previous year, so Lockery and fellow University of Oregon researchers wanted to see how the drug impacted nematodes. They dumped a cannabinoid molecule on the microscopic worms and placed high- and low-calorie foods near them.

The worms swarmed toward the high-calorie bacterial food — a decision Lockery equated to choosing pizza over oatmeal. In a study published Thursday — marijuana’s unofficial holiday of 4/20 — the Oregon researchers determined that worms, like humans, become hungry and develop the munchies when exposed to cannabis.

“It helps us place ourselves in the universe of animals in a new way by reinforcing the commonality between humans, with this massive and marvelous brain, and a tiny little microscopic worm,” Lockery, a biology and neuroscience professor, told The Washington Post.

Around 1990, Lockery began studying the decision-making processes of Caenorhabditis elegans, translucent nematodes with simple brains and no circulatory or respiratory systems.

In June 2016, Lockery was researching how C. elegans decide which bacteria to eat as he and his team began planning their weekly fun experiment. When they thought about the possible impact of marijuana, the researchers thought, “Well, let’s see what happens,” Lockery said.

“We try to keep a sense of humor about what we do, and it keeps us light and creative,” Lockery said. “And this study came initially, in part, from that spirit.”

Marijuana, which contains tetrahydrocannabinol (THC), has long generated hunger in humans by increasing hunger hormones, activating parts of the brain that control hunger and increasing dopamine. Studies have also found that rodents desire high-calorie foods after consuming THC.

In their Oregon lab, researchers poured a cannabinoid called anandamide onto about 50 C. elegans. Scientists transferred the worms into a T-shaped maze and placed high-calorie food on one side and low-calorie food on the other.

While C. elegans usually prefer calorie-dense foods, they ate them at a higher quantity after being exposed to anandamide, and they avoided low-calorie foods more than usual. In follow-up experiments, researchers found that anandamide sparks neurons to become more sensitive to the odors of high-calorie foods.

“This is the first time that the munchies has been demonstrated in an invertebrate organism,” Lockery said. “So this is a big step from what we currently believe to be the sort of limit of the munchies.”

While the Oregon researchers’ study was scheduled to publish last month, Lockery said Current Biology delayed it until 4/20.

Lockery hopes the study will inspire more research into how cannabis influences animals, insects and other organisms. He believes more drugs could be tested on C. elegans to predict how they will affect humans.

Now, Lockery is studying how psychedelics impact worms’ behaviors.

“My project from the beginning had been to try to figure out how a whole — albeit tiny — brain works,” Lockery said. “I didn’t really care much about drugs. I didn’t ever expect that. But I’m grateful for it; it’s been really fun.”