(Val3,Pro8)-Oxytocin, the I3V/L8P variant of oxytocin binding to OT and AVP V1 receptors, is produced by the Saguinus genus of the Callitrichidae family of New World monkeys. When interacting with V1, (Pro8)-OT and oxytocin produce similar signal profiles and are equally effective against Gq and _-arrestin, while (Val3,Pro8)-OT is less effective against _-arrestin. Intranasal application of OT L8P and OT I3V/L8P enhanced parental behavior in rats.