Aβ amyloid cortical and hippocampal pathology in McGill Thy1-APP transgenic (Tg) mice. A1: Absence of Aβ in non-transgenic (Non-Tg) littermate (ccx = cortex; cc = corpus callosum; ca1 = hippocampal ca1 region). A2: Between 1 to 3 mo of age the Tg mice have abundant intracellular Aβ immunoreactive material in the cc and hippocampus. A3: At 6 mo onwards, many mature amyloid plaques became apparent. A4: By 9-10 mo, there are more amyloid plaques. 40 μm thick fixed-frozen section stained with McSA1 antibody (1:4000); Bar = 200 μm. B: At 3 mo, Tg mice (n=6) display cortical proNGF accumulation by Western blot, (p< 0.05), increased MMP-9 activity (gelatin zymography, P< 0.05) and increased expression of iNOS (by western blot, p< 0.05) compared to 1.5 mo old Tg and Non-Tg mice (n=6).