Oxytocin's Partner and Sibling: Vasopressin Zenchronicity

Last week we talked about the peptide oxytocin (OT). This week’s we will explore the other ancient peptide molecule, vasopressin (VP). Oxytocin and VP are genetic and biochemical siblings. Both originated from a single ancestral gene that produced vasotocin. Vasotocin is found in reptiles and other vertebrates and can be measured in the mammalian fetus. OT and VP, with their receptors, function as an integrated, adaptive system, allowing the mammalian body to survive, maintain homeostasis, and reproduce in an ever-changing world.

Sources of individual differences in OT and VP and the sensitivity of their receptors include gender and basic genetic differences. For example, some species, including humans and other socially monogamous mammals, such as prairie voles and dogs, have high levels of OT and an apparent dependence on OT to allow the expression of high sociality and attention to positive social cues. The OT receptor (OTR) and V1 receptor (V1aR) also can be epigenetically tuned by experience, increasing the capacity of OT and VP to have complex adaptive functions.