Circumventricular organs: targets for integration of circulating fluid and energy balance signals?

Physiol Behav. 2013 Sep 10:121:96-102. doi: 10.1016/j.physbeh.2013.02.012. Epub 2013 Feb 28.

Abstract

The subfornical organ (SFO), as one of the sensory circumventricular organs (CVOs), is among the only central nervous system structures which interfaces directly with circulating substances that do not cross the blood brain barrier. Here we describe a growing literature showing that circulating indicators of cardiovascular (angiotensin II, osmolarity, calcium, sodium) and metabolic (adiponectin, amylin, glucose, ghrelin, leptin) statuses influence the excitability of single SFO neurons. Single cell electrophysiological studies from our laboratory have demonstrated excitatory effects of angiotensin II on individual SFO neurons, and changes in angiotensin II receptor expression in this CVO in hypertensive states emphasize the dynamic contribution of SFO neurons to the regulation of fluid balance. Furthermore, we have shown both depolarizing and hyperpolarizing effects of the adipokines adiponectin and leptin in SFO cells, and highlight that conditions of fasting in the case of adiponectin, and obesity in the case of leptin, alter the sensitivity of SFO neurons to these circulating factors. The results examined in this review provide evidence for a role of the SFO as a mediator and integrative structure in the maintenance of cardiovascular and metabolic functions.

Keywords: Adiponectin; Angiotensin II; Circumventricular organs; Energy balance; Fluid balance; Leptin; Subfornical organ.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Cardiovascular Physiological Phenomena*
  • Energy Metabolism / physiology*
  • Humans
  • Neurons / physiology
  • Subfornical Organ / cytology
  • Subfornical Organ / physiology*
  • Water-Electrolyte Balance / physiology*