title: Central angiotensin II stimulation promotes β amyloid production in Sprague Dawley rats.
abstract: BACKGROUND
  Stress and various stress hormones, including catecholamines and glucocorticoids, have recently been implicated in the pathogenesis of Alzheimer's disease (AD), which represents the greatest unresolved medical challenge in neurology. Angiotensin receptor blockers have shown benefits in AD and prone-to-AD animals. However, the mechanisms responsible for their efficacy remain unknown, and no studies have directly addressed the role of central angiotensin II (Ang II), a fundamental stress hormone, in the pathogenesis of AD. The present study focused on the role of central Ang II in amyloidogenesis, the critical process in AD neuropathology, and aimed to provide direct evidence for the role of this stress hormone in the pathogenesis of AD.
  
  
  RESULTS
  Increased central Ang II levels during stress response were modeled by intracerebroventricular (ICV) administration of graded doses of Ang II (6 ng/hr low dose, 60 ng/hr medium dose, and 600 ng/hr high dose, all delivered at a rate of 0.25 µl/hr) to male Sprague Dawley rats (280-310 g) via osmotic pumps. After 1 week of continuous Ang II infusion, the stimulation of Ang II type 1 receptors was accompanied by the modulation of amyloid precursor protein, α-, β-and γ-secretase, and increased β amyloid production. These effects could be completely abolished by concomitant ICV infusion of losartan, indicating that central Ang II played a causative role in these alterations.
  
  
  CONCLUSIONS
  Central Ang II is essential to the stress response, and the results of this study suggest that increased central Ang II levels play an important role in amyloidogenesis during stress, and that central Ang II-directed stress prevention and treatment might represent a novel anti-AD strategy.
authors.affiliation: Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University, Nanjing, People's Republic of China.
authors.forename: Donglin
authors.initials: D
authors.lastname: Zhu
authors.forename: Jingping
authors.initials: J
authors.lastname: Shi
authors.forename: Yingdong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Bianrong
authors.initials: B
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Zhicong
authors.initials: Z
authors.lastname: Chen
authors.forename: Qiang
authors.initials: Q
authors.lastname: Tong
mesh_terms: D000544:Alzheimer Disease; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D002552:Cerebral Ventricles; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D057911:Angiotensin Receptor Antagonists; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D053829:Amyloid Precursor Protein Secretases