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Oxytocin is often called the “love hormone” because it’s considered essential in pairing and maternal care behaviors, but a new study involving the prairie vole calls its role into question.
This research has established that even by removing the receptors linked to this hormone, the small rodent was still able to form strong couples and the mother to conceive and take care of her offspring.
Prairie voles are among the few mammals that pair for life, making them prime subjects for studies devoted to the subject.
In previous research, voles prevented from processing the hormone by administering drugs found themselves solitary and the females could no longer produce milk for their young.
The psychiatrist Devanand Manoli and the neurobiologist Nirao Shah proceeded differently, by producing voles genetically modified in such a way as to deprive them of receptors for oxytocin.
To their surprise the mutant voles had no trouble pairing up with their unmanipulated conspecifics, and the mutant females had no more trouble caring for their young.
A result that suggests that oxytocin is not the primary, let alone sole, driver of a couple relationship and maternal care.
“Genetics reveal that there is no ‘single breaking point’ for behaviors so essential to the survival of species”explained to AFP Mr. Manoli, assistant professor at the University of California in San Francisco.
“Very complex behaviors”
However, the experiment also proved that depriving a partner of an oxytocin receptor was not without consequences, according to the study published Friday in the scientific journal Neuron.
Mutant males mated with ordinary females did not show the expected aggressiveness when confronted with female intruders.
And while mutant females were able to reproduce and care for their offspring, some had fewer offspring, and fewer of them survived than those offspring of normal females.
Young voles from mutant females also weighed less, suggesting their mothers couldn’t raise them as well.
The experiment only involved couples in which only one partner was a mutant and the other a “wild” type, the researchers said, explaining that couples made up only of mutants could give different results.
Either way, the experiment suggests a contrasting role for the hormone in different behaviors.
Animals that grew up without an oxytocin receptor may have developed “other compensatory pathways” that help them pair up and help their young grow, according to Stanford University professor Shah.
Importantly, this research suggests that oxytocin is just one of the genetic factors controlling social behavior in this area.
“I think our study reveals a multiplicity of pathways regulating these very complex behaviors”according to Mr. Manoli.
Oxytocin has sometimes been proposed as a way to treat attachment disorders and other neuropsychiatric conditions, but science is still tentative in this area.
MM. Shah and Manoli hope to learn more about the other hormones and receptors involved in pairing and maternal care.
“These other pathways could serve as therapeutic targets”according to Mr. Manoli.