A new study suggests that the Agouti gene in the brains of male African striped rats may act as a molecular “switch,” making them affectionate or violent toward their offspring.
Active fatherhood is rare in mammals, with only 5% of the 6,000 mammal species having involved fathers. This is why scientists know much less about how paternal care works in mammals than they know about maternal care in mammals.
African striped rats (Rhabdomys pumilio) are useful for studying paternal care in mammals because males exhibit a wide range of behaviors toward their young, from huddling together to keep them warm to actively ignoring their offspring.
In a study last week in Natureresearchers placed male African striped rats in cages, either alone with a group of pups or in group housing with other parents and their respective pups. They found that males kept in groups were more likely to ignore the cubs or try to kill them.
To determine the regions of the brain that mediate this behavior, the team exposed male rats to their pups and then monitored their brain activity. It turned out that attentive parents had greater activity in a region of the brain called the medial preoptic area (MPOA).
“Decades of work have demonstrated that the MPOA acts as a center for maternal care in mammals,” the leader of the investigation, told . Forrest Rogersdo Princeton Neuroscience Institute (USA).
The team dissected the mice’s brains and measured gene activity in MPOA cells. From there, he discovered that a gene called Agouti was more active in males that attacked offspring than in males that cared for them.
“Agouti is best known for its roles in skin pigmentation and metabolism, so discovering this previously unknown role in the brain for parental behavior was exciting,” said the team, in .
As Live Science details, to confirm that Agouti’s expression was responsible for the transition between attentive and aggressive behavior, the team first exposed the mice to their pups and then injected a virus that increased the expression of the Agouti gene in the MPOA.
When the males were exposed to their offspring again, the behavior changed.
“We found that these males, when Agouti was enlarged, became aggressive towards their offspring,” said Rogers, suggesting that this gene was acting as a kind of “switch” that alternated between behavior aggressive and nurturing in rat parents.
“It certainly appears that for some striped mice, increasing Agouti expression is sufficient to induce infanticide. However, we also found that there were other social factors that could also moderate this effect”, warned the investigator.
