Angiotensin II type 1 receptor blocker losartan prevents and rescues cerebrovascular, neuropathological and cognitive deficits in an Alzheimer’s disease model

• Published in: Neurobiology of disease Vol. 68; pp. 126 - 136
• Main Authors: Ongali, Brice, Nicolakakis, Nektaria, Tong, Xin-Kang, Aboulkassim, Tahar, Papadopoulos, Panayiota, Rosa-Neto, Pedro, Lecrux, Clotilde, Imboden, Hans, Hamel, Edith
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2014; Elsevier
• Subjects: Alzheimer Disease - complications; Alzheimer Disease - drug therapy; Alzheimer Disease - genetics; Amyloid; Amyloid beta-Protein Precursor - genetics; Angiotensin II Type 1 Receptor Blockers - pharmacology; Angiotensin II Type 1 Receptor Blockers - therapeutic use; Angiotensin receptor blocker (ARB); Animals; Arginine - analogs & derivatives; Arginine - pharmacology; AT1 receptor; AT4 receptor; Blood Pressure - drug effects; Blood Pressure - genetics; Brain - drug effects; Brain - metabolism; Brain - pathology; Cerebrovascular Circulation - drug effects; Cognition Disorders - drug therapy; Cognition Disorders - etiology; Cognition Disorders - pathology; Disease Models, Animal; Endothelin-1 - pharmacology; Enzyme Inhibitors - pharmacology; FDG-PET; Female; Gene Expression Regulation - drug effects; Humans; Insulin-regulated aminopeptidase (IRAP); Losartan - pharmacology; Losartan - therapeutic use; Male; Memory; Mice; Mice, Transgenic; Mutation - genetics; Neurology; Oxidative stress; FDG-PET; APP; AngIV receptor; RAS; ACh; Memory; superoxide dismutase1; Aβ; AngII; Insulin-regulated aminopeptidase (IRAP); AngIV; angiotensin IV; AD; Alzheimer’s disease; [ 18F]FDG-PET; [ 18F]fluoro-2-deoxy-D-glucose-PET; AT1 receptor; ET-1; angiotensin II; AngII type 2 receptors; mean arterial blood pressure; cerebral blood flow; CGRP; glial fibrillary acidic protein; MAP; renin-angiotensin system; superoxide dismutase 2; N ω-nitro-L-arginine; Oxidative stress; L-NNA; amyloid β peptide; CBF; AngII type 1 receptors; amyloid precursor protein; Amyloid; endothelin-1; WT; AT1; AT2; AT4; angiotensin receptor blockers; cerebral glucose uptake; calcitonin gene-related peptide; Angiotensin receptor blocker (ARB); SOD2; GFAP; SOD1; CGU; AT4 receptor; acetylcholine; ARBs; wild-type; [18F]FDG-PET
• ISSN: 0969-9961; 1095-953X
• DOI: 10.1016/j.nbd.2014.04.018

Abstract Angiotensin II (AngII) receptor blockers that bind selectively AngII type 1 (AT1) receptors may protect from Alzheimer’s disease (AD). We studied the ability of the AT1 receptor antagonist losartan to cure or prevent AD hallmarks in aged (~ 18 months at endpoint, 3 months treatment) or adult (~ 12 months at endpoint, 10 months treatment) human amyloid precursor protein (APP) transgenic mice. We tested learning and memory with the Morris water maze, and evaluated neurometabolic and neurovascular coupling using [18 F]fluoro-2-deoxy-D-glucose-PET and laser Doppler flowmetry responses to whisker stimulation. Cerebrovascular reactivity was assessed with on-line videomicroscopy. We measured protein levels of oxidative stress enzymes (superoxide dismutases SOD1, SOD2 and NADPH oxidase subunit p67phox), and quantified soluble and deposited amyloid-β (Aβ) peptide, glial fibrillary acidic protein (GFAP), AngII receptors AT1 and AT2, angiotensin IV receptor AT4, and cortical cholinergic innervation. In aged APP mice, losartan did not improve learning but it consolidated memory acquisition and recall, and rescued neurovascular and neurometabolic coupling and cerebrovascular dilatory capacity. Losartan normalized cerebrovascular p67phox and SOD2 protein levels and up-regulated those of SOD1. Losartan attenuated astrogliosis, normalized AT1 and AT4 receptor levels, but failed to rescue the cholinergic deficit and the Aβ pathology. Given preventively, losartan protected cognitive function, cerebrovascular reactivity, and AT4 receptor levels. Like in aged APP mice, these benefits occurred without a decrease in soluble Aβ species or plaque load. We conclude that losartan exerts potent preventive and restorative effects on AD hallmarks, possibly by mitigating AT1-initiated oxidative stress and normalizing memory-related AT4 receptors.