High sensitivity of protoplasmic cortical astroglia to focal ischemia.
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.
Lukaszevicz
Anne-Claire
AC
Institut National de la Santé et de la Recherche Médicale, Université Paris XII, Créteil, France.
Sampaïo
Nathalie
N
Guégan
Christelle
C
Benchoua
Alexandra
A
Couriaud
Cécile
C
Chevalier
Elisabeth
E
Sola
Brigitte
B
Lacombe
Pierre
P
Onténiente
Brigitte
B
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
D005904:Glial Fibrillary Acidic Protein