Brain parenchyma vessels and the angiotensin system

It is now recognized that the brain contains an autonomous angiotensin (AG) system, including the aminopeptidases A and N required for angiotensin met abolism. Using immunohistochemical techniques, we show that capillary peric ytes and periendothelial cells of other vessels express aminopeptidase A (A PA) and aminopeptidase N (APN) at their plasma membrane in adult mouse brai n parenchyma. We therefore investigated the localization of angiotensin II( III), known as putative substrates for these enzymes, as well as that of th eir precursor angiotensin I. We report here the presence of immunoreactivit y to angiotensin I and II(III) around most brain vessels. Angiotensins are present at the plasma membrane of brain parenchymal cells, presumably periv ascular astrocytes which are also immunoreactive to AT(1)-receptor antibodi es. The very close relationship between AGII(III) and their metabolizing en zymes APA and APN suggests a specific functional role for brain perivascula r angiotensins. (C) 1999 Elsevier Science B.V. All rights reserved.