Aged eNOS−/− mice display increased APP expression, microglial activation, and impaired spatial memory

Abstract

Aging and other cardiovascular risk factors are associated with increased incidence of Alzheimer's disease (AD). A common feature of cardiovascular risk factors is decreased endothelial nitric oxide (NO). We studied the effect of a loss of endothelial NO on amyloid precursor protein (APP) related phenotype in aged (14–15 month) endothelial nitric oxide synthase deficient (eNOS−/−) mice. APP, β‐site APP cleaving enzyme 1, and amyloid beta (Aβ) levels were significantly higher in the brains of aged eNOS−/− mice as compared to aged wild type mice. APP and Aβ1–40 were increased in hippocampal tissue of eNOS−/− mice as compared to wild type mice. Aged eNOS−/− mice displayed an increased inflammatory phenotype as compared to aged wild type mice. Importantly, aged eNOS−/− mice performed worse in a radial arm maze test of spatial learning and memory as compared to aged wild type mice. These data suggest that chronic loss of endothelial NO may be an important contributor to both Aβ related pathology and cognitive decline. Research was supported by NIH grants HL‐111062 and HL‐91867, the Mayo Alzheimer's Disease Research Center (Z.S.K.), AHA scientist development grant (0835436N, A.V.S.), AHA postdoctoral fellowship 12POST8550003 (S.A.A.), Clinical Pharmacology Training Grant (T32 GM08685) (Trainee S.A.A.), the Samuel Johnson Foundation for Genomics of Addiction Program at Mayo Clinic (D.‐S.C.) and the Mayo Foundation.