Uncovering maternal to paternal communications in mice

Researchers at Japan’s Kanazawa University have proven the existence of communicative signalling from female mice that induces male parental behaviour.

Most mammalian parents use communicative signals between the sexes, but it is uncertain whether such signals affect the levels of parental care in fathers. Scientists have long suspected that female mice play a definite role in encouraging paternal relationships between male mice and their pups.

Now, a research team at Kanazawa University led by Haruhiro Higashida in collaboration with scientists across Japan, Russia and the UK, have proven the existence of auditory and olfactory (smell) signals produced by females which actively trigger paternal activity in males.

Higashida and his team conducted a series of experiments with females and males living in established family groups. Pups were removed from the cage for a short time, while one or both parents remained in the nest. The pups were then returned to the cage, away from the nest. Lone females nearly always brought the pups back to the nest, but lone males were less likely to do so.

Most interestingly, the researchers showed that males were much more likely to retrieve pups when they remained with their mate. This behaviour may be related to ultra-sonic noises emitted by females under stress. These sounds are not emitted by males, pups or non-parental females, and they encouraged the males into parental behaviours. The females also released olfactory signals in the form of pheromones, which triggered the same reaction in the males.

Higashida and his team are keen to expand on their results by analyzing neural signalling in the male brain in response to these female communications.