Fig. 1.

Immunoreactivity for hilar GFAP (A–D) and S100β (E, F) is transiently reduced in CF1 mice after pilocarpine-induced SE. Dentate gyrus paraffin sections of a control mouse (A) and mice 1, 3 and 10 days after SE (B–D, as indicated in the lower right corner) were immunostained for GFAP (brown) and counterstained with hematoxylin (blue). (A) Black arrows point to hilar neurons identified by their size and nucleoli, and pink arrowheads point to representative astrocytes containing oval or round light blue nuclei, defined as healthy (enlarged in inset). (B, C) One and three days after pilocarpine-induced SE, there is loss of GFAP immunoreactivity in the hilus. The remaining GFAP-expressing cells mainly contain dark and shrunken nuclei (pyknotic, pink arrows, enlarged in bottom insets) and only short GFAP-positive processes. GFAP-positive cells in the dentate molecular layer were healthy and overexpressed GFAP 3 days after SE (C, upper inset). (D) Ten days after SE, GFAP-labeled reactive astrocytes with healthy round or oval and light nuclei had reappeared in the hilus (arrows) and mainly in or near the SGZ with processes extending into the hilus (pink arrowheads, inset). (E, F) Immunostaining for S100β (red) in a control mouse (E) and a mouse 3 days after SE (F) shows loss of S100β immunoreactivity and S100β-positive cells in the hilus (yellow arrowheads). In the dentate molecular layer S100β expression is upregulated in the proximal processes of reactive astrocytes. Nuclei are stained with Hoechst 33258 (blue). Note that S100β is expressed in the nucleus, therefore S100β-positive nuclei appear purple. Hilar neurons identified by their larger size are indicated by white arrows. The bars in panel A (valid for B–D) and E (valid for F) represent 50 µm. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)