Figure 2. Mouse prion disease is associated with the accumulation of misfolded prion protein, astrogliosis, spongiosis, and hippocampal neuronal loss.

(A) Lysates from control or prion-infected (10 w.p.i.) mouse hippocampus and cortex were probed in Western blots with an antibody that detected both cellular (PrP^c) and misfolded (PrP^Sc) prion protein. The presence of misfolded PrP^sc is evident by lower molecular weight species in the prion-infected lysates. (B) Lysates from A were treated with proteinase K before probing in Western blots for prion protein. (C) Astrogliosis during prion disease was determined in Western blots of lysates prepared from control mice or mice 9 and 10 w.p.i. and probed with glial fibrillary acidic protein (GFAP), a marker for astrocytes. (D) Immunohistochemical staining of the hippocampal CA1 region probed with anti–glial fibrillary acidic protein antibody (green) to determine the level of astrogliosis. The nuclei were stained blue with DAPI. Scale bars: 50 μm. (E) Spongiosis in prion-infected hippocampi (upper panels) and CA1 region (lower panels) was visualized by H&E stain of mouse hippocampus from paraformaldehyde-fixed mouse brain from control mice injected with NBH (control), prion-infected mice 9 w.p.i., and prion-infected mice 10 w.p.i. Scale bars: 200 μm (upper panels); 100 μm (lower panels). (F) Determination of neuronal loss of pyramidal neurons in the CA1 region of the hippocampus of mice 9 and 10 w.p.i. was determined by immunohistochemical staining of neuronal cell bodies using antibodies to NeuN (green). The nuclei were stained blue with DAPI. Scale bars: 50 μm. (G) Quantification of NeuN staining in the CA1 of mice at various stages of prion disease. Data are shown as mean ± SEM. n = 3 mice, 3 sections per mouse. **P < 0.01; ***P < 0.001, 1-way ANOVA. Blots and images shown are representative of at least 3 independent experiments.