title: Ischemic injury in experimental stroke depends on angiotensin II.
abstract: Since pharmacological interactions of the renin-angiotensin system appear to alter the neurological outcome of stroke patients significantly, we examined the effect of elevated levels of angiotensin II and the role of its receptor subtype AT1 in brain infarction in transgenic mice after focal cerebral ischemia. Angiotensinogen-overexpressing and angiotensin receptor AT1 knockout mice underwent 1 h or 24 h permanent middle cerebral artery occlusion (MCAO). The current study revealed a much smaller penumbra size, i.e., brain tissue at risk, in angiotensinogen-overexpressing animals compared with their wild-type subgroup after 1 h MCAO, but an enlarged infarct size after 24 h. In contrast, a smaller lesion area of energy failure and a much larger penumbral area were found in AT1 knockout mice compared with wild-type littermates. Lower perfusion thresholds for ATP depletion and protein synthesis inhibition after MCAO in AT1-deficient mice and reduced cell damage in an in vitro model using embryonic neurons of AT1 knockout mice suggest injury mechanisms independent of arterial blood pressure. Our data, therefore, demonstrate a direct correlation between brain angiotensin II and the severity of ischemic injury in experimental stroke.
authors.affiliation: Max-Planck-Institute for Neurological Research, Department of Experimental Neurology, Cologne, Germany. thomas.walther@ukbf.fu-berlin.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Walther
authors.forename: Laszlo
authors.initials: L
authors.lastname: Olah
authors.forename: Christoph
authors.initials: C
authors.lastname: Harms
authors.forename: Bjoern
authors.initials: B
authors.lastname: Maul
authors.forename: Michael
authors.initials: M
authors.lastname: Bader
authors.forename: Heide
authors.initials: H
authors.lastname: Hörtnagl
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schultheiss
authors.forename: Günter
authors.initials: G
authors.lastname: Mies
mesh_terms: D000804:Angiotensin II / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000150:complications*; D005260:Female; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000235:genetics / Q000502:physiology; D020521:Stroke / Q000209:etiology / Q000235:genetics*
chemical_list: D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II