Angiotensin receptor blocker use is associated with upregulation of the memory-protective angiotensin type 4 receptor (AT4R) in the postmortem brains of individuals without cognitive impairment
1.Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA ;2.Department of Internal Medicine, Division of Geriatrics, Ankara University School of Medicine, Ankara, Turkey ;3.Department of Medical Biology, Hacettepe University School of Medicine, Ankara, Turkey ;4.Department of Medicine, Division of Geriatrics, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA ;5.Johns Hopkins University Center On Aging and Health, Baltimore, MD, USA ;6.Department of Biostatistics, Bloomberg School of Public Health, Baltimore, MD, USA ;7.National Institute On Aging, National Institutes of Health, Baltimore, MD, USA ;8.Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, USA ;
Abstract:
The reported primary dementia-protective benefits of angiotensin II type 1 receptor (AT1R) blockers (ARB) are believed, at least in part, to arise from systemic effects on blood pressure. However, there is a specific and independently regulated brain renin-angiotensin system (RAS). Brain RAS acts mainly through three receptor subtypes; AT1R, AT2R, and AT4R. The AT1R promotes inflammation and mitochondrial reactive oxygen species generation. AT2R increases nitric oxide. AT4R is essential for dopamine and acetylcholine release. It is unknown whether ARB use is associated with changes in the brain RAS. Here, we compared the impact of treatment with ARB on not cognitively impaired individuals and individuals with Alzheimer’s dementia using postmortem frontal-cortex samples of age- and sex-matched participants (70–90 years old, n?=?30 in each group). We show that ARB use is associated with higher brain AT4R, lower oxidative stress, and amyloid-β burden in NCI participants. In AD, ARB use was associated with lower brain AT1R but had no impact on inflammation, oxidative stress, or amyloid-β burden. Our results may suggest a potential role for AT4R in the salutary effects for ARB on the brains of not cognitively impaired older adults.