When you give a worm weed, it gets hungry, study says

On a Friday afternoon, not long after the US state of Oregon legalized cannabis in 2015, some researchers embarked on a peculiar experiment.

The team worked with a type of tiny nematode worm called Caenorhabditis eleganssmaller than a human eyelash, to understand their food preferences and, on a whim, decided to soak the worms in cannabinoids – the active substances found in the herb.

It turned out that the worms responded, and the cannabinoids made them hungrier for their favorite foods and less hungry for their non-favorite foods. The research turned out to reveal that worms, like humans, engage in hedonic eating – a phenomenon more commonly known as the munchies.

“The very fact of hedonic feeding in nematodes was surprising. Hunger in a worm. Really?” said Shawn Lockery, a professor at the Institute of Neuroscience at the University of Oregon in Eugene and co-author of a study published on Thursday (20) in the scientific journal Current Biology. Previously, cannabinoids were only known to affect humans and other mammals – making them want to eat more and crave the tastiest, highest-calorie foods.

The worms, however, weren’t destroying a pile of junk food. They fed on different types of bacteria.

fluorescent worms

By measuring the worms’ swallowing rate, Lockery and his team determined that the cannabinoids were increasing the amount of a certain mixture of bacteria that the worms ate, making them hungrier. They showed that the worms craved the food they found most palatable by putting them in a T-shaped maze that was baited with a mixture of preferred bacteria and less preferred food.

The worms were also genetically modified so that certain neurons and muscles glow fluorescently, with green dots showing neurons that respond to cannabinoids.

Lockery added that the active ingredients in cannabis caused the worms’ “olfactory neurons to be more sensitive to preferred foods and less sensitive to less preferred foods,” but why this happened was “a big mystery,” so he planned to follow that up.

In humans and other animals, cannabinoids work by binding to cannabinoid receptors in the brain, nervous system and other parts of the body, Lockery said.

These receptors normally respond to related molecules that are naturally present in the body, known as endocannabinoids. The endocannabinoid system plays important roles in feeding, anxiety, learning and memory, reproduction and metabolism. At the molecular level, the cannabinoid system of these worms closely resembles that of people and other animals.

“Our findings help us better understand our place in the animal universe,” Lockery said via email. “It shows that, in at least one respect, the decisions we make are influenced by factors that even a worm can understand.”

ideal lab model

C. elegans It is an ideal laboratory model for studying nerve cells. Despite having a small number of neurons (302 neurons versus 86 billion neurons in humans), worms have a nervous system that includes a primitive brain. It was also the first organism to have its genome sequenced in 1998.

Lockery said the research has the potential to accelerate the discovery of new drugs for metabolic disorders, including obesity.

“Drug discovery often starts with gene discovery, and C. elegans it’s a first-line organism for that,” he said.

“Genetic research in C. elegans it’s fast and cheap. … Our demonstration that the human cannabinoid receptor is functional in regulating worm hunger emphasizes the profound parallels between humans and worms in regulating metabolism.”

What the research really shows, though, is that a “wait, what?” moment on a Friday afternoon may have scientific value.

“We felt that a positive outcome would be fun and thought-provoking for the general public. Science that first makes you laugh, then makes you think,” said Lockery.