title: Mild brain ischemia induces unique physiological properties in striatal astrocytes.
abstract: We studied the properties of GFAP-expressing cells in adult mouse striatum using acute brain slices from transgenic animals expressing EGFP under GFAP promoter. Under physiological conditions, two distinct populations of GFAP-EGFP cells could be identified: (1) brightly fluorescent cells had bushy processes, passive membrane properties, glutamate transporter activity, and high gap junction coupling rate typical for classical astrocytes; (2) weakly fluorescent cells were characterized by thin, clearly distinguishable processes, voltage-gated currents, complex responses to kainate, and low coupling rate reminiscent of an astrocyte subtype recently described in the hippocampus. Mild focal cerebral ischemia confers delayed neuronal cell death and astrogliosis in the striatum. Following middle cerebral artery occlusion and reperfusion, brightly fluorescent cells were the dominant GFAP-EGFP population observed within the ischemic lesion. Interestingly, the majority of these cells expressed voltage-gated channels, showed complex responses to kainate, and a high coupling rate exceeding that of brightly fluorescent control cells. A minority of cells had passive membrane properties and was coupled less compared with passive control cells. We conclude that, in the adult striatum, astrocytes undergo distinct pathophysiological changes after ischemic insults. The dominant population in the ischemic lesion constitutes a novel physiological phenotype unlike any normal astrocyte and generates a large syncytium which might be a neuroprotective response of reactive astrocytes.
authors.affiliation: Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Wang
authors.forename: Giselle
authors.initials: G
authors.lastname: Cheung
authors.forename: Golo
authors.initials: G
authors.lastname: Kronenberg
authors.forename: Karen
authors.initials: K
authors.lastname: Gertz
authors.forename: Shengbo
authors.initials: S
authors.lastname: Ji
authors.forename: Gerd
authors.initials: G
authors.lastname: Kempermann
authors.forename: Matthias
authors.initials: M
authors.lastname: Endres
authors.forename: Helmut
authors.initials: H
authors.lastname: Kettenmann
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000502:physiology*; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology*; D003342:Corpus Striatum / Q000166:cytology / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000502:physiology
chemical_list: D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; C528900:glial fibrillary astrocytic protein, mouse