Brain's 'Parenting Hub' in Male Mice Linked to Diverse Paternal Behaviours
A specific brain region, termed a "parenting hub," has been identified in male mice, correlating with a wide range of paternal behaviours from devoted care to aggression towards pups. This discovery, based on a study of male African striped mice, reveals how neural activity and genetic factors interact to shape parenting styles in these rodents.
Neural Activity and Parenting Styles
The research focused on the medial preoptic area (MPOA) of the brain, which showed significantly increased activity when male mice encountered a pup. However, not all mice exhibited the same level of brain activity. Those displaying nurturing behaviours, such as grooming and nestling pups, had higher neuron activity in the MPOA compared to males who were more standoffish or hostile.
This variation in brain function highlights the complexity of paternal behaviour, with some mice actively engaging in childcare while others ignore or even attack pups, both in wild and laboratory settings.
Role of the Agouti Gene
In addition to brain activity, the study found that males who spent more time caring for pups had lower levels of a specific gene called Agouti in their brains. Dr Forrest Rogers, a postdoctoral researcher at Princeton University in the US, noted, "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."
High levels of Agouti appeared to suppress neural activity in the MPOA, as reported in the journal Nature. This suppression correlated with reduced interest in pups and, in some cases, increased aggression.
Environmental Influences on Behaviour
The research team discovered that environmental conditions significantly influence Agouti levels in the MPOA, which in turn affected behaviour toward pups. Male mice living alone had low levels of Agouti and were more likely to become nurturing adults. In contrast, males living in groups had higher Agouti levels and devoted half as much time to childcare.
When scientists moved some males from communal living arrangements to solitary spaces, Agouti levels dropped, and the males took more interest in pups. This suggests that social environment plays a crucial role in modulating paternal behaviour through genetic mechanisms.
Experimental Manipulations and Implications
Using gene therapy, researchers artificially boosted Agouti levels in the brains of mice. After treatment, males showed less interest in pups upon re-encounter, with some becoming aggressive. This experimental manipulation confirms the gene's role in regulating paternal behaviour.
Co-author Dr Ricardo Mallarino, associate professor of molecular biology at Princeton, explained, "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."
Caution in Human Applications
While both the MPOA and the Agouti gene are found in humans and striped mice, the team cautioned that it remains unknown whether these mechanisms can change paternal behaviour in people. Further research is needed to explore potential parallels in human biology and parenting.
