Simultaneous detection of aquaporin-4 (AQP4) on astrocytic endfeet, glial fibrillary acidic protein (GFAP) revealing a large portion of astroglia and STL in endothelial cells and microglia/macrophages at the ischemic striatum of non-treated rats.

Aquaporin-4-immunostaining (A) in both the vessels and neuropil remained absent at the infarcted tissue and became only visible in the surrounding, apparently less affected tissue, which displayed numerous activated astrocytes as indicated by a strong GFAP-immunoreactivity (A’). This region also contained some vessels stained by STL (A”), but this marker predominantly revealed densely packed microglia/macrophages in the ischemic region. Merging these staining patterns elucidated the complementary occurrence of immune cells and both astroglial markers. At higher magnification (B), the sharp border between a zone with vascular aquaporin-4-immunoreactivity and the infarcted zone devoid of immunosignals became clearly visible. Concomitant GFAP-staining (B’) visualized strongly activated astrocytes with numerous thickened processes reaching the region with densely packed, and STL-labeled microglia/macrophages (B”), which was even better visible after merging the staining patterns (B”‘). Scale bars: in A” and B” = 100 μm, in A”‘ and B”‘ = 50 μm.