Is the 'love hormone' really a love hormone? New study casts doubt

For 40 years, oxytocin has been believed to be the ‘love hormone’ or the ‘cuddle hormone’ which inspires love and social behaviour… but is it?

A new study in prairie voles, which (like humans) were believed to rely on oxytocin receptor signalling to develop social behaviours has turned the idea on its head.

The genetic study shows that the voles can form enduring attachments with mates and provide parental care without oxytocin receptor signalling.

Prairie voles are one of only a few monogamous mammal species.

After mating, they form lifelong partnerships known as "pair bonds".

Pair-bonded voles share parental responsibilities, prefer the company of their partner over unknown members of the opposite sex, and actively reject potential new partners.

Previous studies that used drugs to block oxytocin from binding to its receptor found that voles were unable to pair-bond when oxytocin signalling was blocked.

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But neuroscientists used the gene-editing CRISPR technology to generate prairie voles that lack functional oxytocin receptors.

To their surprise, the mutant voles formed pair bonds just as readily as normal voles.

Devanand Manoli, of the University of California, San Francisco, said, "We were all shocked that no matter how many different ways we tried to test this, the voles demonstrated a very robust social attachment with their sexual partner, as strong as their normal counterparts.”

The mutant voles were also good parents.

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Nirao Shah, of Stanford University, said, "We found that mutant voles are not only able to give birth, but actually nurse.

Both male and female mutants engaged in the usual parental behaviours of huddling, licking, and grooming, and were able to rear pups to weaning age.

Manoli said, "For at least the last 10 years, people have been hoping for the possibility of oxytocin as a powerful therapeutic for helping people with social cognitive impairments due to conditions ranging from autism to schizophrenia.

“This research shows that there likely isn't a magic bullet for something as complex and nuanced as social behaviour."

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