Psilocybin, the active compound in magic mushrooms, significantly reduces aggression and activity in a small, naturally combative fish, according to a new UBC Okanagan-led study.
A new study led by a UBC Okanagan biologist has shown that psilocybin—the active compound in so-called magic mushrooms—significantly reduces aggression and activity in a small, naturally combative fish.
The findings, published in Frontiers in Behavioral Neuroscience, point to new possibilities for using fish as a model to study psilocybin’s therapeutic potential in humans, particularly for conditions involving aggression, anxiety and impaired social functioning.
“We know psilocybin shows real promise for treating depression and anxiety, but its effects on social behaviour are barely understood,” says Dr. Suzie Currie, the study’s senior author and biology professor in the Irving K. Barber Faculty of Science.
“What we’ve shown is that even in a species hard-wired for aggression, a single low dose changes how these animals interact with each other.”
Dr. Currie and her collaborators at Acadia University and Université de Moncton studied the mangrove rivulus (Kryptolebias marmoratus), a small fish found in mangroves of Florida and Central America, with two unusual traits that make it valuable for this kind of work.
It can self-fertilize, producing genetically identical offspring that allow researchers to control for genetic variation. And it’s notably aggressive toward other members of its own species, a trait that gave the team a clear behavioural baseline to measure against.
The researchers paired size-matched fish from different genetic lineages and recorded their interactions before and after the focal fish received a 20-minute waterborne dose of psilocybin.
After treatment, the fish showed significantly less overall movement and far fewer “swimming bursts,” or rapid, aggressive darts toward other fish.
“The fish weren’t sedated or impaired,” says Dr. Currie, who is also UBCO’s Vice-Principal and Associate Vice-President of Research and Innovation. “They were just calmer. They engaged less aggressively with a rival they would normally challenge.”
Fish are an increasingly important tool in neuropharmacology because they share a surprising amount of genetic and physiological architecture with humans, including the serotonin system that psilocybin acts on.
The drug binds to the same family of serotonin receptors in fish brains as it does in human brains, allowing researchers to study how it works at the cellular level in animals that are easier to maintain and observe than mammals.
According to the study, dose analysis showed the resulting concentration of psilocybin’s active form in the fish was comparable to plasma levels measured in humans receiving a low to moderate therapeutic dose.
The next phase of the work will examine serotonin pathways in the fish brain to better understand how psilocybin produces its calming effect.
Dr. Currie cautions that the work is foundational, not clinical.
“Fish models have a strong track record of pointing researchers toward mechanisms that hold up in mammals, including humans. If psilocybin works on aggression in a vertebrate this distantly related to us, that tells us something about how deeply conserved the underlying biology probably is.”
