RESUMEN
Oxytocin (OT) is a 9-amino-peptide hormone synthesized mainly in the Paraventricular Nucleus (PVN) and Supraoptic Nucleus (SON) of mammals'hypothalamus. Small part of OT is synthesized in peripheral organs. In addition to promoting the lactation and uterine contraction, OT has many other physiological functions, such as analgesia. It has been proved that neuropeptide can exert analgesic effect. OT is indeed a neuropeptide secreted naturally by mammals. Sdudies have shown that OT plays an important role in relieving pain and can avoid problems like addiction and other side effects.However, its underlying mechanism of analgia is still unclear. Therefore, further study of the analgesic mechanism of oxytocin has a great theoretic significance and very broad clinical prosperities.