Angiotensin and the Central Nervous System

Angiotensin (Ang) affects the central nervous system (CNS) at several different sites to cause an array of different physiologic effects, including cardiovascular, neuroendocrine, and behavioral responses. Consistent with the diversity of its physiologic actions is the variety of paths it uses to reach its target receptors in the brain. Angiotensin that influences brain function may come from the bloodstream (in which case only neurons that are located in regions lacking the bloodbrain barrier are influenced directly), or it may be synaptically released subsequent to its generation in the brain by glia and possibly neurons. In this analysis, therefore, a distinction is made between the effects of blood-borne Ang II acting on the circumventricular organs of the brain (which are devoid of a blood-brain barrier) and the effects of Ang that may be released as a neurotransmitter or neuromodulator from neurons within the CNS, although the neural pathways subserving these two aspects of central Ang action may not be completely independent.