Emerging features of brain angiotensin receptors

In mammalian brain, angiotensin II AT(1) and AT(2) receptor subtypes are apparently expressed only in neurons and not in glia. AT(1) and AT(2) receptor subtypes are sometimes closely associated, but apparently expressed in different neurons. Brain AT(1)/AT(2) interactions may occur in selective cases as inter-neuron cross talk. There are two AT(1) isoforms in rodents, AT(1A), which predominates, and AT(1B). There are also important inter-species differences in receptor expression. Relative lack of amino acid conservation in the gerbil gAT(1A), receptor substantially decreases affinity for the AT(1) antagonists. AT(1) receptors are expressed in brain areas regulating autonomic and hormonal responses. AT(1A) receptors are heterogeneously regulated in a number of experimental conditions. In specific areas. AT(1A) receptors are not normally expressed, but are induced under influence of reproductive hormones in dopaminergic neurons. There are AT(1) and AT(2) receptors also in areas related to limbic, sensory and motor functions and their expression is developmentally regulated. A picture is emerging of widespread, neuronally localized, heterogeneously regulated, closely associated brain angiotensin receptor subtypes, modulating multiple functions including neuroendocrine and autonomic responses, stress, cerebrovascular flow, and perhaps brain maturation, neuronal plasticity, memory and behavior. (C) 1999 Elsevier Science B.V. All rights reserved.