The fraction isolated from extract of the posterior lobe of the PITUITARY GLAND, which stimulates intestinal activity, constricts blood vessels, and inhibits the secretion of URINE. It is also known as the antidiuretic hormone (ADH) because of this last effect, and is used in the treatment of DIABETES INSIPIDUS. An artificially produced analogue is used in the treatment of ENURESIS (bed-wetting) in children.