Artikel
Nestin-expressing cells adopt a complex electrophysiological phenotype following mild ischemic episode
Nestin positive Zellen erwerben einen komplex elektrophysiologischen Phänotyp nach milder ischämischer Episode
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
Text
Objective
The intermediate filament nestin is upregulated in response to cerebral ischemia, the significance of this, however, is incompletely understood. The present study was designed to describe in a comprehensive immunohistochemical and electrophysiological approach the effects of mild transient ischemia on nestin-expressing cells in the striatum up to 8 weeks following occlusion and reperfusion of MCA.
Methods
Here, we used transgenic mice that express green fluorescent protein (GFP) under control of the nestin promotor to characterize the fate of nestin-expressing cells up to 8 weeks following 30 min occlusion of the middle cerebral artery (MCAo) and reperfusion. Immunofluorescent triple labeling was carried out on 40-μm-free-floating sections using a spectral confocal microscope.
Results
The population of nestin-GFP+ cells increased in the ischemic lesion rim and core within 4 days, did not become TUNEL-positive and were detectable up to 8 weeks in the lesion scar. Nestin-GFP+ cells proliferated in situ and underwent approximately one round of cell division. They were not recruited in large numbers from the subventricular zone (SVZ) as indicated by absence of co-labeling with intracerebroventricularly injected dye DiI in the majority of nestin-GFP+ cells and absence of migration chains. Nestin-GFP+ cells expressed the chondroitin sulfate proteoglycan NG2 and nestin protein, but typically lacked astrocytic markers, i.e. glial fibrillary acid protein (GFAP) or S100ß. Vice versa, the majority of GFAP+ cells lacked nestin-expression and surrounded the ischemic lesion by 4 days. Whole cell patch clamp recordings in acute brain slices from controls demonstrated that about half of the cells had complex membrane properties and expressed AMPA receptors but lacked glutamate transporters similar to progenitor cells and a newly described subpopulation of astrocytes. 4 days after the insult all nestin-GFP+ cells expressed these properties.
Conclusions
We hypothesize that the change in physiological properties induced by the ischemic insult is directed toward a network function and early neuronal differentiation of nestin-expressing cells.