NAS attenuates neuronal cell death in PHNs and OHSCs. Neuronal cell death of PHNs and OHSCs induced by 3 h OGD or 18 h H₂O₂ (1000 μmol/L for PHNs and 1500 μmol/L for OHSCs) with or without NAS was evaluated by the LDH assay (A–D). PHNs (A, B) and OHSCs (C, D) were preincubated with NAS for 2 h. Data from three independent experiments are graphed, and statistically significant differences are indicated with *p < 0.05 and **p < 0.01. NAS (15 μm) inhibited cell death in OHSCs exposed to OGD (E) and H₂O₂ (F), and PI fluorescence images were obtained. Hippocampal slices under normal control conditions displaying background PI fluorescence (E, F, left). Intense PI labeling in OHSCs exposed to OGD and H₂O₂ mainly occurred in the CA1, CA3 pyramidal cell field as well as dentate gyrus (E, F, middle). NAS significantly attenuated PI labeling, demonstrating neuroprotective effects (E, F, right). Scale bars: top lanes, 0.5 mm; middle and bottom lanes, 0.1 mm.