Physiological characteristics of proliferating progenitors after mild transient brain ischemia

Transgenic mice expressing green fluorescent protein (GFP) under control of different precursor cell promotors represent a powerful new tool for detailed morphological and electrophysiological research. Here, we subjected mice expressing GFP under control of the nestin-, doublecortin- and glial fibrillary acid protein (GFAP)-promoters to 30min occlusion of the middle cerebral artery (MCAo) and subsequent reperfusion. Animals were followed over different time intervals ranging from 24 hrs to 4 weeks after MCAo. Following ischemia, we observed increased precursor cell proliferation and morphological changes in the different cell types. This was accompanied by characteristic alterations of membrane properties in precursor cell populations in striatum. Furthermore, following ischemia a new type of GFAP-expressing brightly fluorescent astrocyte emerged characterized by complex membrane properties and a high rate of gap junctional coupling, two features not observed concurrently in astrocytes so far.