Center Role of the Oxytocin-Secreting System in Neuroendocrine-Immune Network Revisited

The hypothalamic neuroendocrine system has extensive and bidirectional interactions with immune system. In parallel with the hypothalamic-pituitary-adrenal axis, the oxytocin-secreting system composed of hypothalamic oxytocin neurons and their associated neural tissues has also emerged as a major part of the neuroendocrine center that regulates immunologic activities of living organisms. This oxytocin neuron-immune network can synthesize and release many cytokines and oxytocin while being the target of both oxytocin and cytokines by the mediation of corresponding receptors. Pathogens and cytokines along with the humoral and neural activities induced by them provide afferent input onto oxytocin neurons while oxytocin, cytokines and autonomic nervous systems convey efferent signals from the oxytocin-secreting system to the immune system. Serving as an integrative organelle, the oxytocin-secreting system coordinates all neural, humoral and immunologic signals to change immunologic activities through releasing oxytocin into the brain and blood to minimize pathological injury and secure the functional stability of our body. Oxytocin exerts these effects through strengthening surface barriers and maintaining immunologic homeostasis involving both humoral immunity and cellular immunity. In this review, we revisit the novel concept: the oxytocin-secreting system is the center structure in the oxytocin neuron-immune network.