Octopuses take ecstasy for science and become more social creatures

Give a little MDMA to an octopus and the usually solitary creature will open right away. This is according to the research published today in Current Biology.

In the study, researchers at Johns Hopkins Medical donated MDMA, a drug known as ecstasy, to a group of two-point octopus in California. The genome of this octopus is well understood, making it an ideal study.

In the end, octopuses – and virtually every animal on the planet, except ants and bees – have a specific serotonin transporter. In humans, this carrier regulates mood and, when exposed to MDMA, relaxes social inhibitions, which partly explains why Ecstasy is so popular as a group drug. It is also thought to play a role in social functioning.

Gül Dölen, one of the co-researchers on paper, wanted to test if this would allow this same answer in this particular octopus, known for his solitary lifestyle. It is one of the first MDMA tests to use a non-mammalian subject – not to mention invertebrates.

"People who study the brains of mammals, and especially those who study the human brain, find it easy to reject flies and worms," ​​Dölen says, dismissing them because these simpler creatures do not possess the complexity of more species. advanced. Cephalopods are the family that includes octopuses, however, which are known for their intelligence. "It's really hard to dismiss that with an octopus because they are very intelligent and are capable of all sorts of sophisticated things, and they have a brain very different from mammals," says Dölen. Despite the big differences between humans and octopus, the carrier seemed to work in much the same way.

MDMA was administered to five male octopuses and one female octopus, which were then placed in the same tank. Octopuses have also received an object with which to distract themselves. Normally, they can opt for this "toy" and avoid any contact with members of their species except for the breeding season. Although there has been a notorious tendency to socialize with the female octopus, male octopuses have socialized under certain conditions, which was virtually unknown outside of the aggressive scenarios in nature.

"What we found, is that when the animals were just saline, they preferred to spend time with the object rather than the other, but after the MDMA, they preferred it. another octopus on the object ", explains Dölen.

MDMA, generally considered a group drug, has emerged in recent years as a potential treatment for PTSD and clinical depression, through the regulation of mood and social behavior. "It's a very exciting therapy, but we really do not know how it works and what it does," says Dölen. "We know the first steps, but we do not know much about serotonin transporter binding and the treatment of your PTSD." But seeing how it works in mice, octopuses and other animals helps researchers understand how it fits into the evolution of all animals on Earth. Even solitary ones.

"I think what this suggests to me, in any case, is that the social behavior is there for these octopus," says Dölen. "They have it, but it's so important for their ability to adapt to their environment that they turn it off."

She then wants to advance the research to two other species of octopus, the large striped Pacific octopus and the pygmy octopus. The first is known to be an octopus which, unlike some of its brothers, is very social, ranging up to live in colonies and keep the same companion for long periods. This behavior is closer to the cuttlefish, another cephalopod known for its social behavior.

Giving the drug to other social creatures could help better understand the serotonin transporter and its role in almost all animals on Earth. After all, vertebrates did not appear until 500 million years ago, which means that nature has seen fit to keep this adaptation for a long time before that.

"The dinosaurs came and went in the interval we are talking about," says Dölen. "It's been part of our genetic makeup for so long that it may explain why social behaviors are so important to humans."