Jeff Probst on 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). Jeff Probst 2016.