Search

Publisher Summary This chapter discusses molecular cloning, characterization, molecular mechanism, and regulation of the vasopressin receptor of corticotroph pituitary cells. The identification and characterization of the V3 receptor as a new type of vasopressin receptor has allowed better understanding of the action of vasopressin (AVP)-regulated adrenocorticotropic hormone (ACTH) secretion by pituitary corticotrophs. V3 receptor modulates AVP actions in numerous tissues, many of which are autocrine or paracrine. In the pituitary, V3 receptor regulation is related to corticotroph responsiveness and plays an essential role to preserve this responsiveness in the presence of elevated glucocorticoids, such as in chronic stress or Cushing's disease. Chronic stressors that are associated with increased responsiveness, such as repeated hypertonic saline intraperitoneal injections or repeated immobilization stress, are associated with increased anterior pituitary V3 receptor expression. This upregulated pituitary expression is not only detected at the messenger RNA (mRNA) level but also at the level of membrane receptors, demonstrated by increased AVP binding.