A new study in Current Biology has found that nematode worms C. elegans have the same response to cannabinoids as humans do. The study found that the nematodes become hungrier for foods they like and less hungry for foods they are just OK with, which is similar to the effects of marijuana on human appetites, i.e., the phenomenon known as the 'munchies.'
Researchers from the University of Oregon conducted the study after cannabis became legal in Oregon in 2015. They used nematodes in their research because, while they diverged from the lineage leading to mammals over 500 million years ago, they retained the response to cannabinoids. Shawn Lockery, one of the paper authors from the University of Oregon in Eugene, noted, "It is truly remarkable that the effects of cannabinoids on appetite are preserved through this length of evolutionary time."
The team wanted to see if cannabinoids have a similar effect across species as they do in humans. They found that the cannabinoid system in nematodes is similar to that in humans and other animals. At the molecular level, it was found that cannabinoids alter the sensitivity of an important food-detecting olfactory neuron in nematodes. Lockery said, "Upon cannabinoid exposure, it becomes more sensitive to favored food odors and less sensitive to non-favored food odors. This effect helps explain changes in the worm's consumption of food, and it is reminiscent of how THC makes tasty food even tastier in humans."
The researchers found that the effects of anandamide, an endocannabinoid, depend on the presence of the worms' cannabinoid receptors. The team went further to test this result and genetically replaced the C. elegans cannabinoid receptor with the human cannabinoid receptor. Under these conditions, they found that the worms responded as they normally did to cannabinoids.
"Cannabinoid signaling is present in the majority of tissues in our body," Lochery said, "It therefore could be involved in the cause and treatment of a wide range of diseases." Therefore, the discovery of the human cannabinoid receptor gene being functional in nematodes "sets the stage for rapid and inexpensive screening for drugs that target a wide variety of proteins involved in cannabinoid signaling and metabolism." The team believes that the findings have significant practical implications and provide an opportunity to examine how drugs can alter perception and psychological well-being in both humans and different animal species.
Cover Photo: A genetically engineered worm. (Image Credit: Stacy Levichev LICENSE: CC BY-SA)
Sources: EurekAlert!, Current Biology