The Neurohypophysis

Abstract

Vasopressin (Antidiuretic hormone, ADH) is the antidiuretic principle secreted by the supraoptic and paraventricular nuclei of the hypothalamus. Arginine vasopressin (AVP) is an octapeptide with a basic amine at the penultimate position of the side chain. The hypothalamus also secretes a polypeptide called neurophysin, which is believed to be a carrier protein involved in the intraneuronal transport of arginine vasopressin. Arginine vasopressin is transported through the pituitary stalk and is stored in the posterior pituitary. The median eminence of the hypothalamus represents a crucial location in this avenue of transport. Section of the pituitary stalk above the median eminence permanently disrupts the pathway, resulting in permanent loss of antidiuretic hormone.