Fig. 4

Immunocytochemical analysis of BACE1 and APP. a, b Primary cortical neurons grown on coverslips were treated with 2.5 μM Aβ oligomers (Aβ-O) for 3 days, followed by immunofluorescence staining with anti-BACE1 (a) or anti-APP (b) antibodies. Immunostaining of control and Aβ-O-treated cells was carried out under the same conditions, and their images were acquired at the same exposure time. Scale bar = 20 μm. Intensity of BACE1 immunoreactivity is relatively higher in neurites, but not soma of neurons treated with Aβ-O than control. c, d Fluorescence intensities of BACE1 (c) or APP (d) in soma and neurites were separately quantified as described in Methods, and the relative levels depicted on a graph. (n = 18 ~ 20, ***p < 0.001). e Fluorescence intensities of BACE1 in axons and dendrites were separately quantified as above in specimens doubly immunostained with BACE1 and MAP2, and the relative levels depicted on a graph (n = 24, *p < 0.05, **p < 0.01)