Octopuses On Ecstasy Reveal Commonalities with Humans

Just as in people, the drug stimulates the animals to behave more socially.

Sep 21, 2018
Shawna Williams

How do you study the neuroscience of a creature whose brain bears little resemblance to that of humans? One approach, detailed yesterday (September 20) in Current Biology, is to see how the animal reacts to MDMA—also known as the street drug ecstasy. Johns Hopkins University researchers Gül Dölen and Eric Edsinger report that the drug induced social behavior in California two-spot octopuses (Octopus bimaculoides), much as it does in humans, suggesting similar roles for serotonin signaling in intelligent life throughout the animal kingdom.

“I was absolutely shocked that it had this effect,” Judit Pungor, a neuroscientist at the University of Oregon who was not involved in the research, tells NPR.

Octopuses are more closely related to snails than to humans, and their brains are organized very differently—they lack a cerebral cortex, for example. “It’s a little bit like studying alien intelligence,” Dölen tells National Geographic. “It can potentially tell us a lot about the ‘rules’ for building a nervous system that supports complex cognitive behaviors, without getting bogged down in the incidental organization of brains.” 

The genome for the California two-spot octopus was sequenced a few years ago, and in this study, Dölen and Edsinger found that it contains a gene similar to SLC6A4, which in humans encodes a serotonin transporter that binds to MDMA. That docking stimulates the release of serotonin, a neurotransmitter linked, among other things, to mood and social behavior.

To explore how the octopus version of the receptor functions, the researchers borrowed seven of the animals from Woods Hole Marine Biological Laboratory and devised a behavioral test for them. After dunking them in either a saltwater bath or a solution of MDMA, they put the octopuses in an enclosure with a toy at one end and another, caged octopus at the other.

Octopuses are not social animals, and before they received the drug, “[t]hey mashed themselves against one wall, very slowly extended one arm, touched the [other animal], and went back to the other side,” Dölen tells The Atlantic. But after the MDMA bath they spent more time near the other animal, and, she tells National Geographic, "they tended to hug the cage and put their mouth parts on the cage. . . . This is very similar to how humans react to MDMA; they touch each other frequently." 

One takeaway, Dölen tells NPR, is that "serotonin has been encoding social functions for a very, very long time. At least 500 million years ago, it started doing this function."

It’s possible the behavior could be explained by something other than social impulses, the University of Lethbridge’s Jennifer Mather, who was not involved in the study, tells The Atlantic. She suggests the drug could have affected the animals’ perception of chemical cues. “There’s no proof that it is anything more than attraction.” 

“Octopuses really are the best example we have on Earth of a second intelligence,” San Francisco State University neuroscientist Robyn Crook tells the magazine. The similarities they show with humans in the new study indicate, she says, that “there are only so many ways to make an intelligent brain.” 

Correction (September 21): The original version of this article described the protein coded for by SLC6A4 as a receptor; it is in fact a transporter. The Scientist regrets the error.

June 2019

Living with Bacteria

Can pathogens be converted to commensals?


Sponsored Product Updates

Sartorius debuts the Intellicyt iQue3 at CYTO® 2019
Sartorius debuts the Intellicyt iQue3 at CYTO® 2019
Sartorius will be showcasing the latest addition to its cellular analysis portfolio on booth #103 at this year’s CYTO® conference and exhibition, with the launch of the Intellicyt iQue3. 
Expedeon AG introduces Lightning-Link Metal Labeling Kits to support single cell analysis
Expedeon AG introduces Lightning-Link Metal Labeling Kits to support single cell analysis
Novel antibody labeling immunoassay technology for multiplex immune profiling addresses one of the fastest growing, billion-dollar life science market sectors
Best Practices: Calculating Cell Confluency
Best Practices: Calculating Cell Confluency
In this white paper, learn how to use a cell imager system to directly and accurately capture and calculate cell confluency!
LabTwin's AI-powered Digital Assistant Now Talks Back and Connects Data Sources in the Lab with New Open API
LabTwin's AI-powered Digital Assistant Now Talks Back and Connects Data Sources in the Lab with New Open API
LabTwin GmbH, the world's first voice and AI-powered digital lab assistant, today announced its new open API that will connect scientists with data sources both inside and outside of the lab.