The vole, faithful in love, with or without oxytocin

Iural voles are models of attachment. Monogamous throughout their lives, living as a couple, the partners share educational and household tasks, protect themselves against external aggressions, console each other in the event of a hard blow. A rarity among mammals. Quite the opposite of their mountain vole cousins, inveterate frolickers, making fun of their young like a jinx. Nearly thirty years ago, scientists showed that the two species, which are extremely close, differed mainly in the density of receptors for oxytocin, known as the attachment hormone, and for another neuropeptide, vasopressin. So that Microtus ochrogaster, the scientific name of the grassland species, became the main animal model for the study of the role of oxytocin, all the more valuable as the importance of the same hormone in human social and affective relations was affirmed.

However, in a study published in the journal Neuron, January 27, American researchers come to disturb this pretty picture. The team led by Nirao Shah and Devanand Manoli, professors of psychiatry respectively at Stanford University and the University of California San Francisco (UCSF), showed that our gentle rodents could form emotional bonds even in the absence oxytocin receptors. An unexpected discovery and even “disconcerting”admits Nirao Shah.

Gene inactivation

The research program pursued essentially methodological goals. It involved using the Crispr-Cas9 molecular scissors to inactivate genes not in mice or rats, a now common practice, but for the first time in voles. New tools and new protocols had been developed, the embryos had been isolated, genetically modified, then reimplanted in the mothers. The researchers therefore hoped to find the results observed by the medicinal methods, namely that a vole without oxytocin lost its attachment bonds.

And flop! They found that the modified animals continued to form pairs, that the females carried their pregnancies to term and that the pairs took care of the young. Breastfeeding was only partially impaired. “I still remember our amazement, adds Devanand Manoli. But three different mutations of the oxytocin receptor carried out in three separate laboratories led to the same result. This convinced us. »

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