Vasopressin signaling and vasopressin-to-oxytocin receptor crosstalk in the regulation of parental caregiving behavior.

Mammalian neonates are born in an immature state and require caregiving from conspecific adults for survival. A growing body of evidence indicates that multiple neuronal populations and hormonal factors regulate parental caregiving behavior. Among these, arginine vasopressin (AVP) and oxytocin (OT) have received particular attention. While the role of OT has been extensively investigated, the functional contributions of AVP remain comparatively less understood. Recent neurobiological studies in rodents have begun to elucidate the molecular, cellular, and circuit-level mechanisms through which AVP regulates caregiving behavior. In this review, I first summarize the properties of AVP and its receptors, with particular emphasis on vasopressin-to-oxytocin receptor crosstalk, a phenomenon in which AVP can activate non-canonical oxytocin receptors. I then review past and recent findings on the role of AVP signaling in parental caregiving behavior, highlighting evidence that receptor crosstalk contributes to these effects. Based on these findings, I propose a hypothetical circuit model integrating AVP and OT signaling in the regulation of caregiving behavior. Finally, I discuss unresolved questions regarding receptor specificity, temporal dynamics, and circuit mechanisms, as well as the potential relevance of these findings to human parenting.