Chapter 8 - Oxytocin and Vasopressin

Abstract

Oxytocin and vasopressin can increase milk output, the main mechanism being the emptying of the myoepithelial elements of the mammary gland. There can no longer be any doubt that oxytocin controls milk ejection, and it is generally accepted that milk ejection is mediated mainly by a humoral mechanism—the release of oxytocin in response to suckling. For many years, the pharmacological activities of oxytocin and vasopressin were found to be overlapping. The milk-ejecting activity, like oxytocin activity, is an intrinsic property of vasopressin. The milk-ejection reflex may be excited by various kinds of conditioned stimuli, but it is also subject to inhibition by emotionally stressful situations in women as well as in cows.