SMO theory: A comprehensive review of oxytocin secretion via serotonin and melatonin pathways

The secretion of oxytocin, a neuropeptide critical for social bonding, emotional regulation, and reproductive processes, is influenced by complex neuroendocrine pathways. Among these, the serotonin and melatonin pathways have garnered significant attention for their roles in modulating oxytocin release. The Serotonin-Melatonin-Oxytocin (SMO) Theory proposes a synergistic interaction between these neurotransmitters and hormones, with serotonin acting as a precursor to melatonin and both regulating oxytocin secretion through circadian rhythms and neurochemical signaling. This review provides a comprehensive analysis of current research on the serotonin and melatonin pathways in relation to oxytocin release. We explore the molecular mechanisms involved, the influence of circadian rhythms, and the broader physiological and behavioral implications of the SMO pathway. Additionally, the review discusses how dysregulation of this system may contribute to mood disorders, stress responses, and social behavior abnormalities. By integrating findings from neurobiology, chronobiology, and endocrinology, this paper aims to provide a holistic understanding of the SMO pathway and its critical role in oxytocin secretion.