title: Attenuation of brain damage and cognitive impairment by direct renin inhibition in mice with chronic cerebral hypoperfusion.
abstract: The role of the renin-angiotensin system in cognitive impairment is unclear. This work was undertaken to test our hypothesis that renin-angiotensin system may contribute to cognitive decline and brain damage caused by chronic cerebral ischemia. C57BL/6J mice were subjected to bilateral common carotid artery stenosis with microcoil to prepare mice with chronic cerebral hypoperfusion, a model of subcortical vascular dementia. The effects of aliskiren, a direct renin inhibitor, or Tempol, a superoxide scavenger, on brain damage and working memory in these mice were examined. Chronic cerebral hypoperfusion significantly increased brain renin activity and angiotensinogen expression in C57BL/6J mice, which was attributed to the increased renin in activated astrocytes and microvessels and the increased angiotensinogen in activated astrocytes in white matter. Aliskiren pretreatment significantly inhibited brain renin activity and ameliorated brain p67(phox)-related NADPH oxidase activity, oxidative stress, glial activation, white matter lesion, and spatial working memory deficits in C57BL/6J mice with bilateral common carotid artery stenosis. To elucidate the role of oxidative stress in brain protective effects of aliskiren, we also examined the effect of Tempol in the same mice with bilateral common carotid artery stenosis. Tempol pretreatment mimicked the brain protective effects of aliskiren in this mouse model. Posttreatment of mice with aliskiren or Tempol after bilateral common carotid artery stenosis also prevented cognitive decline. In conclusion, chronic cerebral hypoperfusion induced the activation of the brain renin-angiotensin system. Aliskiren ameliorated brain damage and working memory deficits in the model of chronic cerebral ischemia through the attenuation of oxidative stress. Thus, direct renin inhibition seems to be a promising therapeutic strategy for subcortical vascular dementia.
authors.affiliation: Department of Pharmacology and Molecular Therapeutics, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.
authors.forename: Yi-Fei
authors.initials: YF
authors.lastname: Dong
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Kataoka
authors.forename: Kensuke
authors.initials: K
authors.lastname: Toyama
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sueta
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Koibuchi
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Yamamoto
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yata
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tomimoto
authors.forename: Hisao
authors.initials: H
authors.lastname: Ogawa
authors.forename: Shokei
authors.initials: S
authors.lastname: Kim-Mitsuyama
mesh_terms: D000577:Amides / Q000494:pharmacology; D000808:Angiotensinogen / Q000378:metabolism; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001925:Brain Damage, Chronic / Q000453:epidemiology / Q000378:metabolism / Q000517:prevention & control*; D002545:Brain Ischemia / Q000378:metabolism*; D003072:Cognition Disorders / Q000453:epidemiology / Q000378:metabolism / Q000517:prevention & control*; D003497:Cyclic N-Oxides / Q000494:pharmacology; D015140:Dementia, Vascular / Q000378:metabolism*; D004195:Disease Models, Animal; D005650:Fumarates / Q000494:pharmacology; D006973:Hypertension / Q000150:complications; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018696:Neuroprotective Agents / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D012083:Renin / Q000378:metabolism*; D012084:Renin-Angiotensin System / Q000187:drug effects / Q000502:physiology; D012307:Risk Factors; D013113:Spin Labels; D000092502:Renin Inhibitors
chemical_list: D000577:Amides; D000808:Angiotensinogen; D000959:Antihypertensive Agents; D003497:Cyclic N-Oxides; D005650:Fumarates; D018696:Neuroprotective Agents; D012083:Renin; D013113:Spin Labels; D000092502:Renin Inhibitors; C446481:aliskiren; C001803:tempol