Central vasopressin: dendritic and axonal secretion and renal actions.

Abstract

On a daily basis, practising nephrologists evaluate hyponatremic or, on the opposite side, polyuric states using physio-pathological concepts related to central vasopressin secretion and water conservation by the kidneys. The purpose of this review is to highlight new basic and clinical developments describing the hypothalamic release and peripheral renal actions of the antidiuretic hormone, arginine-vasopressin. The classical vasopressin neuroendocrine pathway involves the axonal release of vasopressin from the neurohypophysis directly into the circulation. From there, vasopressin acts on V1 and V2 receptors to regulate blood volume and peripheral resistance. In the second neuronal pathway, vasopressin is released from axonal projections of paraventricular parvocellular neurons into the rostral ventrolateral medulla, nucleus tractus solitarius and intermediolateral column of the spinal cord, areas responsible for the integration of peripheral sympathetic and vagal outflow [1, 2] (Figure 1). A third source of vasopressin is the neuronal cell bodies and dendrites of vasopressinergic neurons [3]. Open in a separate window Fig. 1. Osmoregulatory circuits in the mammalian brain and the periphery. Neurons and pathways are color-coded to distinguish osmosensory, integrative and effector areas. Afferent pathways from the OVLT to ACC are responsible for thirst perception. Centralpreautonomic neurons in the PVN are responsible for the increased renal sympathetic activity mediated by perception of dehydration by magnocellular cells in closed proximity (see Figure 1). ACC, anterior cingulate cortex; AP, area postrema; DRG, dorsal root ganglion; IML,intermediolateral nucleus; INS, insula; MnPO, median preoptic nucleus; NTS, nucleus tractus solitarius; OVLT, organum vasculosum laminae terminalis; PAG, periaqueductal grey; PBN, parabrachial nucleus; PP, posterior pituitary; PVN, paraventricular nucleus; SFO, subfornical organ; SN, sympathetic nerve; SON, supraoptic nucleus; SpN, splanchnic nerve; THAL, thalamus; VLM, ventrolateral medulla. Reproduced from ref [1] with permission.