Vasopressin/Oxytocin Receptor Antibodies

Vasopressin and oxytocin receptors are activated by the endogenous cyclic nonapeptides vasopressin (AVP) and oxytocin (OT). These peptides are derived from precursors which also produce neurophysins. Vasopressin and oxytocin differ at only 2 amino acids (positions 3 and 8). Four receptors exist in mammals, three for AVP and a unique receptor for OT, although AVP possesses a nanomolar affinity for all subtypes. AVP is also named the antidiuretic hormone (ADH) due to its effect on the regulation of water body balance whereas oxytocin is defined as the "quick birth" hormone because of its highly potent uterotonic activity. AVP has multiple physiological functions, including body water regulation, control of blood pressure, platelet aggregation, release of coagulation factors, cell proliferation, and effects on body temperature, insulin release, corticotropin release, memory and social behaviour. All these actions are mediated through activation of three specific membrane-bound receptors present at the surface of the target cells. On the basis of pharmacological and functional studies, these receptors have been classified as V1A, V1B and V2 subtypes. The neurohypophysial peptide oxytocin facilitates reproduction in all vertebrates at several levels via activation of the OT receptor.