Angiotensin II: a peptidergic neurotransmitter in central autonomic pathways

Over the past 20 years a growing body of evidence has been directed to establishing the roles of angiotensin II (ANG) within the central nervous system. When this work began in the late 1970s the concept that this circulating hormone may also act as a neurotransmitter within the brain was contrary to the established dogma regarding synaptic transmission. There is now substantial anatomical data describing the distribution of ANG receptors, and the biochemical machinery for the production of this peptide, within the CNS. In addition many studies have described physiological and cellular consequences of activation of these receptors by both exogenous administration and endogenous release of ANG. Data from single cell studies are now also beginning to elucidate both signal transduction pathways and ion channels, influenced as a consequence of peptide actions at these receptors. These observations effectively establish the status of ANG as a chemical messenger (neurotransmitter) used for synaptic communication by specific populations of CNS neurons.