<unk>  is primarily known for its role as a mammalian circadian output. The most common product of<unk>  is vasopressin, which is a neurohypophysial hormone that is important in homeostatic mechanisms and processes, like cortical EEG rhythms. Its other products are neurophysin II and copeptin.<unk>  is produced in a specific type of neuron called magnocellular neurons (MCNs), which are located in the hypothalamus. In mammals, the<unk>  is also transcribed in the suprachiasmatic nucleus where its expression is under the control of the circadian TTFL. It is well established that the finished vasopressin product is transported from the cell body to the terminals in the posterior pituitary gland where it is released into the bloodstream as a result of environmental stressors like dehydration.<unk>  Regulation<unk>  regulation is controlled by the TTFL. In this system, per2 protein is transcribed and phosphorylated by the CK1E enzyme. Accumulation of this protein inhibits the transcription factors Clock and BMAL1, so that no additional per product is created. At the same time, per2 inhibits the transcription factors driving the<unk>  so that its expression and products are reduced. It can be noted that<unk>  expression is regulated by the TTFL in the SCN but not in the paraventricular nucleus of the hypothalamus (PVH) and supraoptic nucleus (SON). Receptor Pathways The transcription of the<unk>  commonly results in the binding of vasopressin to one of three vasopressin receptors:<unk> R1A,<unk> R1B, and<unk> R2. When vasopressin binds to<unk> R1A, a G-protein coupled receptor (GPCR), phospholipase C (PLC) becomes activated. This pathway typically involves regulating vasoconstriction. When vasopressin binds to<unk> R1B, a GPCR, the phosphatidylinositol-calcium second messenger system is stimulated.<unk> R1A and<unk> R1B are GPCRs that stimulate PLC to promote the production of DAG which activates PKC and IP3 and stimulates calcium ion release from the ER. This signaling pathway is important in regulating homeostasis and the amount of water, glucose, and salts within the blood via ACTH release and storage. When vasopressin binds to<unk> R2, another GPCR, adenylyl cyclase is stimulated. This second messenger pathway involves the regulation of ADH, or vasopressin, in the kidneys, which has an important diuretic purpose of retaining water and manipulating the concentrations of soluble toxic wastes and urea in urine.<unk>  in rats Within rats, the<unk>  is important for the regulation of various processes associated with the excretory system and smooth muscle cells. The<unk>  and arginine vasopressin are commonly colocalized with oxytocin because synaptic transmission of oxytocin regulates the expression of<unk>  mRNA. In one study conducted by Greenwood and colleagues, researchers found that<unk>  expression in rats is regulated by the cAMP responsive element-binding protein-3 like-1 (CREB3L1). CREB3L1 is activated when it is cleaved and when the<unk>  is translocated from the Golgi to the nucleus. Additionally, CREB3L1 mRNA levels correspond with increased amounts of transcription of the<unk>  in the hypothalamus following a deficiency of sodium and as a consequence of diurnal rhythm in the SCN. Both full-length and constitutively active forms of CREB3L1 (CREB3L1CA) induce the expression of rat<unk>  promoter-luciferase reporter constructs whereas a dominant-negative mutant reduces expression. From this study, the researchers concluded that CREB3L1 is a regulator of<unk>  transcription in the hypothalamus and specifically within the PVH and SON. Arginine vasopressin stimulates the process of phosphorylation of aquaporin 2 (AQP2) of renal tissue which contributes to the overall increased permeability of water in the collecting duct cells of the tissue. The phosphorylation of AQP2 leads to activation of the protein kinase A signaling pathway which amplifies the permeability of water by stimulating the rat equivalent of the urea transporter 1 protein.
AVP gene
GNAS complex locus
Growth hormone secretagogue receptor
Human β-globin locus
Cystic fibrosis transmembrane conductance regulator
Mothers against decapentaplegic homolog 4
Y chromosome
BGR-34