GFAP status in cerebral cortex, striatum/mesencephalon, cerebellum, and hippocampus. (A-D) Densitometry analysis of immunoblots prepared from lysates of cerebral cortex, striatum/mesencephalon, cerebellum and hippocampus of WT (white bars) and Ctsk-/- mice (grey bars) as indicated. Representative immunoblots are shown in the lower panels; lanes represent separate individuals. (A) GFAP levels in the cerebral cortex showed a significant increase of approximately 76% in Ctsk-/- mice compared to WT (A, Ctsk-/- n = 10; WT n = 13). (B) No significant difference was observed in the amount of GFAP in striatum/mesencephalon (B, Ctsk-/- n = 10; WT n = 10). (C) No alterations were observed in GFAP levels in cerebellum (C, Ctsk-/- n = 10; WT n = 12). (D) GFAP levels were significantly decreased in hippocampus of Ctsk-/- mice, reaching approximately 60% of the values observed in WT (D, Ctsk-/- n = 10; WT n = 10). (E-O) Developmental status of astrocytes in the hippocampus. (E) Overview of a horizontal section through the hippocampus that was immunostained for GFAP to detect mature astrocytes, illustrating the analyzed regions. (F-O) Confocal laser scanning micrographs of sections immunolabeled against GFAP showed strongly decreased staining intensity in samples from Ctsk-/- mice as compared to WT. The same pattern could be observed in the dentate gyrus (F, G), CA3 region (H, I), CA2 region (J, K), and CA1 region (L, M). (N, O) Higher magnification images of astrocytes in the CA1 area. In contrast to the dense astrocytic profiles observed in WT, those of Ctsk-/- mice appeared much thinner and less ramified (arrows). Bars - 200 μm in (E), 50 μm in (F-O). Fluorescence micrographs are displayed in reverse contrast. Levels of significance are denoted as ** for p < 0.01.