title: High sensitivity of protoplasmic cortical astroglia to focal ischemia.
abstract: The generally accepted concept that astrocytes are highly resistant to hypoxic/ischemic conditions has been challenged by an increasing amount of data. Considering the differences in functional implications of protoplasmic versus fibrous astrocytes, the authors have investigated the possibility that those discrepancies come from specific behaviors of the two cell types. The reactivity and fate of protoplasmic and fibrous astrocytes were observed after permanent occlusion of the medial cerebral artery in mice. A specific loss of glial fibrillary acidic protein (GFAP) immunolabeling in protoplasmic astrocytes occurred within minutes in the area with total depletion of regional CBF (rCBF) levels, whereas "classical" astrogliosis was observed in areas with remaining rCBF. Severe disturbance of cell function, as suggested by decreased GFAP content and increased permeability of the blood-brain barrier to macromolecules, was rapidly followed by necrotic cell death, as assessed by ultrastructure and by the lack of activation of the apoptotic protease caspase-3. In contrast to the response of protoplasmic astrocytes, fibrous astrocytes located at the brain surface and in deep cortical layers displayed a transient and limited hypertrophy, with no conspicuous cell death. These results point to a differential sensitivity of protoplasmic versus fibrous cortical astrocytes to blood deprivation, with a rapid demise of the former, adding to the suggestion that protoplasmic astrocytes play a crucial role in the pathogenesis of ischemic injury.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Université Paris XII, Créteil, France.
authors.forename: Anne-Claire
authors.initials: AC
authors.lastname: Lukaszevicz
authors.forename: Nathalie
authors.initials: N
authors.lastname: Sampaïo
authors.forename: Christelle
authors.initials: C
authors.lastname: Guégan
authors.forename: Alexandra
authors.initials: A
authors.lastname: Benchoua
authors.forename: Cécile
authors.initials: C
authors.lastname: Couriaud
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Chevalier
authors.forename: Brigitte
authors.initials: B
authors.lastname: Sola
authors.forename: Pierre
authors.initials: P
authors.lastname: Lacombe
authors.forename: Brigitte
authors.initials: B
authors.lastname: Onténiente
mesh_terms: D001253:Astrocytes / Q000145:classification / Q000473:pathology* / Q000648:ultrastructure; D001812:Blood-Brain Barrier / Q000502:physiology; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology* / Q000648:ultrastructure; D002560:Cerebrovascular Circulation / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D002546:Ischemic Attack, Transient / Q000473:pathology*; D007700:Kinetics; D009457:Neuroglia / Q000473:pathology; D012039:Regional Blood Flow / Q000502:physiology
chemical_list: D005904:Glial Fibrillary Acidic Protein