Abstract 224: Chronic Infusion Of Angiotensin-(1-7) Alleviates Cerebral Hemorrhagic Injury Compromised By Angiotensin II

Abstract

Angiotensin-(1-7) [Ang-(1-7)] is a potential vascular protective peptide which counteracts the effects of Ang II. In this study, we investigated the role of Ang-(1-7) in hemorrhagic stroke. Adult male C57BL/6 mice implanted with telemetric probe for recording arterial blood pressure (BP) were divided into four minipump treatment groups: saline, Ang II, Ang II + Ang-(1-7), Ang II + Ang-(1-7) + A-779. After 2 weeks of treatment, mice were subjected to induction of hemorrhagic stroke by microinjection of collagenase (type VII; 0.075 U in 0.5 μL) in striatum. Mice were sacrificed at twenty-four hours after ICH induction. Brains were dissected and cut into coronal slices for histological analysis of middle cerebral artery (MCA)remodeling and hemorrhagic size. The plasma levels of tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein 1 (MCP-1) and interleukin (IL-8) were determined by ELISA and the levels of NFκB and inhibitor of kappa B (IκB) in cerebral microvasculature were determined by western blot. We found (Figure): 1) Ang II increased BP, MCA remodeling and hemorrhagic size. 2) Ang-(1-7) significantly decreased the effects of Ang II on MCA and hemorrhage without affecting the BP, which were abolished by A-779. 3) Ang-(1-7) induced a 26-32% reduction in plasma level of TNF-α, MCP-1 and IL-8 increased by Ang II. 4) Ang-(1-7) also counter-regulated Ang II-induced NFƙB up-regulation and IƙB down-regulation. In conclusion, Ang-(1-7) counteracts Ang II on vascular remodeling and hemorrhagic injury by alleviating NFκB-related inflammation.