Aβ-mediated neurotoxicity was attenuated by PAM. A. Cortical neurons alone or co-cultured with PAM were treated with vehicle or 20 μM Aβ25-35 for 24 h. The nucleus is stained with DAPI (blue) and TUNEL assay (red), and the co-localization of nuclei and TUNEL-positive staining is found in apoptotic cells. B. The percentage of apoptosis as determined by DAPI staining (the % of cells with nuclear condensation) and TUNEL assay in cortical neurons alone (closed columns) and co-cultured with PAM (open columns). The results are the mean ± S.D. from four independent experiments. Significant differences between neurons without and with PAM under the same treatments are indicated by #, P < 0.05. Significant differences between vehicle-treated neurons and PAM-co-cultured neurons are indicated by *, P < 0.05. C. After treatment with vehicle or Aβ25-35 for 24 h, the cells were loaded with calcein-AM and confocal images were taken with a confocal fluorescence microscope. The experiment was performed four times. The graph shows the number of beaded neurites per 16 μm2 area in neurons alone (closed columns) and neurons co-cultured with PAM (opened columns). The results are the mean ± S.D. from four independent experiments. Significant differences between vehicle-treated cells and Aβ-treated cells co-cultured with microglia are indicated by *, P < 0.05. Significant differences between cortical neurons with and without PAM are indicated by #, P < 0.05.