Mechanistic insights into Aβ effects on neural stem cell proliferation and differentiation.

Amyloid-β (Aβ) accumulation impairs hippocampal neural stem cell (NSC) function, but whether Aβ biases NSC lineage commitment toward the astrocytic lineage remains unclear. In this study, primary hippocampal NSCs from neonatal Sprague-Dawley rats were treated with 60 μM Aβ25-35 fragment, close to the 48-h half-maximal inhibitory concentration (IC50 ≈ 57.8 μM) determined by a CCK-8 assay. After 48 h, the proportions of Nestin+ and 5-ethynyl-2'-deoxyuridine (EdU)+ cells were significantly decreased (P < 0.01 and P < 0.001, respectively). After 7 days of differentiation, the proportion of glial fibrillary acidic protein (GFAP)+ cells was significantly increased (P < 0.001). GFAP+ cells exhibited an increased number of processes but shortened process length. Western blotting confirmed decreased Nestin and increased GFAP protein levels (both P < 0.01). Network-based bioinformatics screening identified 124 overlapping genes between Aβ-related targets and NSC-associated genes, with the PI3K-Akt pathway most highly enriched; validation showed a reduced p-Akt/Akt ratio (P < 0.01), decreased p-GSK-3β (Ser9) and β-catenin levels (P < 0.001), and upregulated total GSK-3β (P < 0.05). Taken together, these findings indicate that Aβ25-35 inhibits NSC proliferation and promotes astrocytic lineage differentiation, at least partly through suppression of the PI3K/Akt/GSK-3β/β-catenin pathway.