vasopressine

Vasopressine, also known as vasopressin or antidiuretic hormone (ADH), is a peptide hormone that regulates body water balance and vascular tone. In humans, it is produced by magnocellular neurons in the hypothalamus and released from the posterior pituitary in response to physiological cues.

Vasopressine is a nonapeptide with the sequence Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly, linked by a disulfide bond between the first and sixth residues. It acts by binding to G protein–coupled receptors: V1 receptors (V1A and V1B) mediate vasoconstriction and ACTH release, while V2 receptors in the kidney collecting ducts promote water reabsorption by triggering the insertion of aquaporin-2 channels into the apical membrane of principal cells.

Regulation of vasopressine release is driven mainly by plasma osmolality and, to a lesser extent, by blood volume and pressure. Osmoreceptors in the hypothalamus detect increases in osmolality and stimulate ADH release, reducing urine output. Baroreceptors and volume receptors in the cardiovascular system respond to decreases in blood pressure or volume by increasing ADH secretion, helping to preserve circulatory stability. Alcohol and certain medications can suppress ADH release, contributing to increased urine production.

Clinically, insufficient vasopressine activity causes central diabetes insipidus, characterized by excessive dilute urine and thirst, whereas kidney insensitivity leads to nephrogenic diabetes insipidus. Excessive ADH secretion can cause hyponatremia, as seen in SIADH. Desmopressin is a synthetic V2-selective analog used to treat central DI and certain bleeding disorders, while vasopressin and its analogs may be used as vasopressors in shock under careful medical supervision.