The structure, distribution and function of the receptors for the neurohypophysial hormones arginine8-vasopressin (AVP) and oxytocin (OT) is being investigated. The cDNAs for the rodent and human AVP receptor subtypes (V1a, V1b, and V2), and the OT receptor have been isolated. Stable expression of the cloned receptors in mammalian cells has allowed functional studies (ligand binding properties, signal transduction mechanisms) to be performed. Expression of the receptor genes in rat and human brain regions and peripheral tissues is being determined by northern blot analysis, in situ hybridization histochemistry, and reverse transcription (RT)-polymerase chain reaction (PCR). These studies have revealed that the V1b receptor gene is expressed in extrapituitary sites in rats and humans, and the gene encoding the V2 receptor is expressed outside the kidney in humans but not adult rats, and point to novel functions for these receptors.
