Vasopressin at Central Levels and Consequences of Dehydration.

Disorders of water balance are a common feature of clinical practice. An understanding of the physiology and pathophysiology of central vasopressin release and perception of thirst is the key to diagnosis and management of these disorders. Mammals are osmoregulators; they have evolved mechanisms that maintain extracellular fluid osmolality near a stable value, and, in animal studies, osmoregulatory neurons express a truncated delta-N variant of the transient receptor potential vannilloid (TRPV1) channel involved in hypertonicity and thermal perception while systemic hypotonicity might be perceived by TRPV4 channels. Recent cellular and optogenetic animal experiments demonstrate that, in addition to the multifactorial process of excretion, circumventricular organ sensors reacting to osmotic pressure and angiotensin II, subserve genesis of thirst, volume regulation and behavioral effects of thirst avoidance.