Study of male mice could offer answers about differing parenting styles

A specific brain region, dubbed a "parenting hub", has been linked to the diverse paternal behaviours of male mice, from devoted care to aggression towards pups.

Changes within this area, alongside varying levels of a particular gene, correlate with distinct parenting styles in male African striped mice.

These rodents display a wide spectrum of involvement, both in the wild and in labs; some actively groom and nestle pups, while others ignore or even attack them. The study found the brain's medial preoptic area (MPOA) became significantly more active when male mice encountered a pup.

But not all mice showed the same brain activity, with those who are caring towards pups showing higher levels of neuron activity compared to male mice who were more “standoffish” or hostile.

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Researchers also found that males who spent more time caring for pups had lower levels of a specific gene called Agouti in their brains.

“Agouti is better known for its roles in skin pigmentation and metabolism, so discovering this previously unknown role in the brain for parenting behaviour was exciting,” said Dr Forrest Rogers, a postdoctoral researcher at Princeton University in the US.

The researcher team also found that certain environmental conditions influence Agouti levels in the MPOA, which in turn affected behaviour toward pups.

If males lived alone, they had low levels of Agouti and were more likely to become nurturing adults, the researchers said.

But male mice that lived in groups had higher levels of Agouti, and devoted half as much time to childcare.

High levels of Agouti appeared to suppress neural activity in the MPOA, the research team report in the journal Nature.

The scientists also used gene therapy to artificially boost Agouti levels in the brains of mice.

They found that when males re-encountered pups after treatment, they showed less interest in pups than they had before, with some even becoming aggressive.

The scientists also found that making changes to the environment also led to changes in levels of Agouti.

They moved some males from communal living arrangements to solitary spaces and found that Agouti levels dropped and males took more interest in pups.

“Our findings point to Agouti as a potential evolutionary mechanism that allows animals to integrate environmental information, such as social competition or population density, and adjust the balance between self-preservation and investment in offspring,” said co-author Dr Ricardo Mallarino, associate professor of molecular biology at Princeton.

The MPOA and the Agouti gene are both found in humans and striped mice, but the team cautioned that it remains unknown whether these mechanisms can change paternal behaviour in people.