Activation of NF-κB by Aβ in rat cerebellar granule cells. Primary neuronal cells were treated with 100 nM Aβ-(1–40) (d-f) and Aβ-(25–35) (g-i) for 45 min or left untreated (a-c). (a, d, g) Indirect immunofluorescence analysis of cell cultures for p65 NF-κB immunoreactivity using the activity-specific α-p65 mAb (28) and a Cy3-conjugated second antibody (see Materials and Methods). (b, e, h) DNA staining of nuclei in cell cultures using DAPI. (c, f, i) Phase contrast micrographs. N, neurons; A, astrocytes. (Bar = 50 μm.)