Oxytocin is a cyclic peptide containing 9 amino acid residues. In its molecule, we find several amide groups (-CONH), which were formed through peptide bonds between amino acids. It is produced in the paraventricular nuclei of the hypothalamus by the magnocellular neurons but is released only in the neurohypophysis. Oxytocin is a fundamental importance in birth labor and the ejection of milk. Oxytocin acts on labor by stimulating uterine contractions, as well as dilating the vaginal canal and distancing the pubic symphysis. The suction promoted by the babies in the halo of the mother's breast also promotes the release of oxytocin, whose function is to help in the secretion of milk.
