vasopressin
n. a peptide hormone produced in the paraventricular nucleus and supraoptic nucleus of the hypothalamus and released by the posterior pituitary gland into the blood as controlled by osmoreceptors. It has two forms that differ by a single amino acid—lysine vasopressin (LVP) in pigs and arginine vasopressin (AVP) in humans and all other mammals—and that bind to one of three distinct receptors, called V1a, V1b, and V2. Both forms increase fluid retention in the body by signaling the kidneys to reabsorb water instead of excreting it in urine, and they raise blood pressure by signaling specific smooth muscle cells to contract and narrow small blood vessels. Beside these and other physiological functions, vasopressin modulates complex cognitive functions—such as attention, learning, and the formation and recall of memories—and may also modulate emotion.
Additionally, vasopressin and the chemically related peptide hormone oxytocin have been implicated in a range of mammalian social behaviors, such as aggression, territoriality, maternal and paternal care, pair-bond formation and mating, social recognition, attachment, affiliation, and vocalization, as well as components of human-specific social behaviors and disorders (e.g., autism). Vasopressin itself may be involved in the pathophysiology of anxiety disorders, including posttraumatic stress disorder, and has been implicated in the pathophysiology of depression as well. AVP secretion appears to play a critical role in the stress response through activation of the hypothalamic–pituitary–adrenal axis (HPA axis): In times of stress, the HPA axis secretes corticotropin-releasing factor and AVP to stimulate the release of corticotropin from the anterior pituitary gland synergistically, culminating in a rise in
circulating glucocorticoids. Vasopressin is produced synthetically (e.g., desmopressin) for such therapeutic purposes as helping the body conserve fluids (e.g., in the treatment of diabetes insipidus), restoring blood pressure (e.g., in the treatment of hypotension), and facilitating blood clotting (e.g., in the treatment of hemophilia). Also called antidiuretic hormone (ADH).