Oxytocin is a naturally occurring hormone first associated with pregnant and breast feeding mothers. It’s role appears to be helping mothers bond with their new born babies. Extensive research into the hormone in recent years has revealed that oxytocin plays a significant role in all kinds of social relationships and interactions, enabling those with high levels to be more trusting of others and to also receive more trust from others.
According to Wikipedia :
Oxytocin has peripheral (hormonal) actions, and also has actions in the brain. Its actions are mediated by specific, oxytocin receptors. The oxytocin receptor is a G-protein-coupled receptor that requires magnesium and cholesterol. It belongs to the rhodopsin-type (class I) group of G-protein-coupled receptors.
Studies have looked at oxytocin’s role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, and maternal behaviors.