Oxytocin changes primate paternal tolerance to offspring in food transfer.

Oxytocin facilitates social recognition in rats and mice, onset of maternal behavior in virgin mice and formation of pair bonds without copulation in prairie voles. However, the relationship between this peptide and paternal behavior in primates remains largely unknown. We investigated whether oxytocin affects paternal behavior in common marmosets. In these primates, fathers as well as mothers take care of their infants, and transferring food to the infants is one of their more obvious caretaking behaviors. We tested whether oxytocin and an oxytocin receptor antagonist affect the transfer of food to offspirng by fathers. After intracerebroventricular infusion of the vehicle, oxytocin, or the oxytocin receptor antagonist, the fathers' behavior, including picking up food, transferring food to the offspring, and refusing to transfer food to the offspring, was analyzed. Compared with the vehicle, oxytocin reduced the frequency of refusal. This was not caused by reduction of appetite. Although the oxytocin receptor antagonist did not change the frequency of refusal behavior of the fathers statistically significant manner, these observations suggest that the tolerance of the adult male marmoset toward its offspring as shown by the transfer of food is increased by oxytocin administered into the central nervous system.