Vasopressin in central autonomic regulation

The hypothalamic paraventricular nucleus (PVN) is the most important central site for the integration of autonomic function, and the main source of vasopressin (VP). It is well known that VP is being released in the blood stream from axons of magnocellular neurons (MCNs) to act as a key hormone in control of volemia and blood pressure at the periphery. However, it is less known that VP is also being synthesized in parvocellular neurons (PCNs) whose axons travel to the medulla and spinal cord wherefrom PCNs modulate the autonomic nervous system in control of vital functions. VP is also being released from somata and dendrites of MCNs to act locally as autocrine regulator. From there, it can diffuse to the parvocellular division, stimulate V1a receptors on PCNs, and coordinate endocrine and autonomic response of the PVN to complex challenges. In this chapter different modes of release and communication by VP that participate in central autonomic control of the circulation will be elaborated, as well as the contribution of VP to the deleterious hyperadrenegic condition associated with cardiovascular diseases.