Sexual or paternal experiences alter alloparental behavior and the central expression of ERα and OT in male mandarin voles (Microtus mandarinus)

Various hypotheses have been proposed to explain factors influencing male alloparental behavior in cooperatively breeding species. Mandarin voles (Microtus mandarinus) are ideal animal models to investigate these factors because they are highly social rodents and display biparental care and spontaneous parental care when exposed to foster pups. Here we test the idea that the sexual and paternal experience of males influences alloparental behavior toward novel pups, and that these experiences alter the expression of neuropeptide oxytocin (OT) and estrogen receptor alpha (ERα). Alloparental behavior and OT and ERα expression were compared between virgin males that had no prior sexual or reproductive experience, exposed males that with prior exposure to novel pups before the test, paired males that had been housed with a female, and new fathers having their first litter with a female. Our results show that prior exposure to novel pups and prior mating and paternal experience increased male alloparental behavior toward a novel pup. This experience also increased OT expression and affected the expression of ERα. This study reveals important initiation factors for male alloparental behavior and suggests a relationship between alloparental behavior and central OT expression in males.