Hormone / Fertility
Investigational
Oxytocin Acetate
Also known as: Pitocin, Syntocinon, OXT
Naturally occurring nine-amino acid peptide hormone. Studied in oxytocin-receptor signalling research.
Research overview
Oxytocin (also written OXT; licensed medicines include Syntocinon and Pitocin) is a nine-amino-acid peptide hormone with a disulphide ring. It is made in the hypothalamus and released from the posterior pituitary, and it acts on the oxytocin receptor (OXTR), found in the uterus, breast tissue, brain and other tissues. Its established physiological roles are in labour and milk let-down, and it is used as a licensed medicine in obstetrics. From the mid-2000s, studies giving oxytocin intranasally reported effects on trust and social behaviour, but many of these findings have not replicated: methodological reviews found most were small and underpowered, and a large 24-week placebo-controlled trial in children and adolescents with autism found no difference from placebo (Sikich et al., NEJM 2021). How much intranasally given oxytocin reaches the brain is still debated. Oxytocin is heat-sensitive, which led to the development of carbetocin, a longer-acting, heat-stable analogue. Supplied for laboratory research use only.
Mechanism of action
Oxytocin binds the oxytocin receptor (OXTR), a G-protein coupled receptor that signals mainly through Gq proteins and raises calcium inside the cell. In the uterus this drives muscle contraction, and in breast tissue it drives milk ejection. OXTR is also present in several brain regions, where its roles are studied mainly in animal models. At higher concentrations oxytocin also acts on vasopressin receptors.