L-368,899 hydrochloride is primarily used in research settings as a selective oxytocin receptor antagonist. It is widely applied in studies to understand the physiological and behavioral roles of oxytocin, a hormone involved in social bonding, stress response, and reproductive functions. Researchers utilize this compound to block oxytocin receptors, allowing them to investigate its impact on social behaviors, maternal-infant bonding, and anxiety-related responses. Additionally, it has been explored in preclinical studies to examine its potential therapeutic applications in conditions such as autism spectrum disorder, postpartum depression, and other disorders linked to oxytocin dysregulation. Its use helps to elucidate the complex mechanisms of oxytocin signaling in the brain and body.