Oxytocin has no definite known role in men, although it may aid contraction of the seminal vesicles of the testis. In women, it contracts the pregnant uterus, although it is not the sole initiator of parturition. During lactation, oxytocin promotes milk ejection by contraction of smooth muscle in the breast ducts - an effect that is mediated by a neurohormonal reflex. Oxytocin also influences ovarian function. Like vasopressin, oxytocin is released from the median eminence and may affect the anterior pituitary. The response of gonadotrophins to the gonadotrophin-releasing hormone (GnRH) appears to be modified by oxytocin. There is tentative evidence to suggest that oxytocin increases lipolysis in the adipocyte and that it may affect cerebral function.
