From the Guidelines
There are three main types of vasopressin receptors: V1a, V1b, and V2 receptors, which play crucial roles in various physiological and pathological processes, including vasoconstriction, antidiuretic effects, and stress responses.
Types of Vasopressin Receptors
The V1a receptors are primarily found in vascular smooth muscle, liver, and platelets, where they mediate vasoconstriction, glycogenolysis, and platelet aggregation 1.
- V1b receptors are mainly located in the anterior pituitary and central nervous system, where they regulate ACTH secretion and have roles in stress responses.
- V2 receptors are predominantly expressed in the collecting ducts of the kidney and are responsible for the antidiuretic effects of vasopressin by increasing water reabsorption through aquaporin-2 water channels. These receptors function through different signaling pathways: V1 receptors (both a and b) act through phospholipase C and calcium mobilization, while V2 receptors operate via adenylyl cyclase and cAMP 1.
Clinical Implications
Understanding these receptor subtypes is important for developing targeted therapies for conditions like diabetes insipidus, hyponatremia, and certain types of shock where vasopressin signaling plays a crucial role.
- The use of vasopressin receptor antagonists, such as conivaptan and tolvaptan, has been shown to improve serum sodium concentration in patients with hypervolemic hyponatremia 1.
- However, the long-term safety and benefit of these therapies remain unknown, and further research is needed to fully understand their clinical implications.
Signaling Pathways
The signaling pathways of these receptors are complex and involve various downstream effectors.
- V1 receptors activate phospholipase C, leading to an increase in intracellular calcium and subsequent vasoconstriction.
- V2 receptors activate adenylyl cyclase, leading to an increase in cAMP and subsequent antidiuretic effects. Overall, the types of vasopressin receptors and their signaling pathways play critical roles in maintaining homeostasis and responding to various physiological and pathological stimuli.
From the FDA Drug Label
Vasopressin causes vasoconstriction by binding to V1 receptors on vascular smooth muscle coupled to the Gq/11-phospholipase C-phosphatidyl-inositol-triphosphate pathway, resulting in the release of intracellular calcium. In addition, vasopressin stimulates antidiuresis via stimulation of V2 receptors which are coupled to adenyl cyclase. At lower concentrations typical for the antidiuretic hormone vasopressin inhibits water diuresis via renal V2 receptors. In addition, vasopressin has been demonstrated to cause vasodilation in numerous vascular beds that are mediated by V2, V3, oxytocin and purinergic P2 receptors Vasopressin at pressor doses triggers contractions of smooth muscles in the gastrointestinal tract mediated by muscular V1-receptors and release of prolactin and ACTH via V3 receptors
The types of vasopressin receptors are:
- V1 receptors: found on vascular smooth muscle, coupled to the Gq/11-phospholipase C-phosphatidyl-inositol-triphosphate pathway
- V2 receptors: found in the renal system, coupled to adenyl cyclase, and also mediate vasodilation in some vascular beds
- V3 receptors: mediate release of prolactin and ACTH, and contractions of smooth muscles in the gastrointestinal tract 2
From the Research
Types of Vasopressin Receptors
- The vasopressin receptors are classified into several types, including:
- V1a receptor: associated with vasoconstriction and coupled to Gq protein and phospholipase C 3
- V1b receptor: involved in the regulation of the corticotroph axis and also coupled to Gq protein and phospholipase C 3
- V2 receptor: responsible for water reabsorption in the renal collecting duct and coupled to Gs protein and adenylyl cyclase 3
- V3 pituitary receptor: mentioned in the context of vasopressin receptors, but its specific function is not detailed in the provided studies 4
- Additionally, there is a mention of a putative AVP V(1c) receptor, which is described as having a vasodilating effect, but this is not extensively discussed in the provided studies 5
- The oxytocin receptor is also mentioned as a separate entity, with its own set of agonists and antagonists, and is involved in various physiological processes, including uterine contraction and social behavior 5
Characteristics and Functions
- The V1a and V1b receptors are involved in different physiological processes, with the V1a receptor playing a role in circulatory shock states and the V1b receptor regulating the corticotroph axis 4, 3
- The V2 receptor is crucial for water reabsorption in the kidneys, and mutations in this receptor can lead to diabetes insipidus 3
- The vasopressin receptors have distinct signaling pathways and tissue distributions, which are important for their physiological effects 4