The ability of MDMA to stimulate prosocial behavior in octopuses pointed to the antiquity of the mechanisms of action of serotonin.
Among other effects of taking the psychoactive substance MDMA (ecstasy), pronounced pro-social behavior and irrepressible friendliness are often noted. It is believed that this is due to the accumulation in the synapses of serotonin - "the hormone of happiness", which plays a large role in strengthening social relationships, stimulating empathy. MDMA inhibits the work of a transport protein, which normally removes "spent" serotonin molecules from interneuronal synapses.
Several years ago, Johns Hopkins University School of Medicine biologist Eric Edsinger co-authored Octopus bimaculoides' DNA sequencing work. Analyzing it, the scientists found that cephalopods also have a gene close to the human gene for the SERT transport protein.
This made it possible to directly test whether serotonin is involved in stimulating prosocial activity in octopuses. After all, if this is so, then the mechanism must be incredibly ancient: the evolutionary paths of mammals and cephalopods diverged more than half a billion years ago. The results of the work of Edsinger and colleagues were presented in the journal Current Biology.
The octopus O. bimaculoides was placed in the central compartment of the aquarium, behind one partition of which was an interesting toy for curious cephalopods, and behind the other - a relative tied with a net so that he could not interfere with the experiment. For starters, the experimental octopuses measured a "baseline" level of friendliness - based on the interest that the mollusc showed in a particular section of the aquarium and the time spent in it. It should be said that this level, by our standards, is not high: almost all octopuses are exceptional loners.
Setting up the experiment.
During the experiments, octopuses were placed in a container containing a weak solution of MDMA for 10 minutes, and then in an experimental aquarium. Indeed, in comparison with the baseline indicators, such cephalopods showed unexpected sociability and spent more time communicating with an unexpected “neighbor”, actively touching it with their tentacles.
"Despite the anatomical difference between the human brain and the octopus, we have shown that there are many similarities between them in the work of the gene for the protein - the serotonin transporter," add the authors of the work.
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Sergey Vasiliev