Figure 6

Effect of ZnO NPs on apoptosis in cultured primary astrocytes. (A) Fluorescent images of chromosome condensation by DAPI staining. Control cells (left), cells exposed to 12 μg/ml of ZnO NPs for 6 h (middle). Cells were pretreated for 1 h with 5 mM of NAC before 6 h co-exposure with 12 μg/ml ZnO NPs (right). Scale bar, 50 μm. Magnification, ×400. (B) FACS results of the Annexin V-FITC and PI assays. Cells were treated with 4, 8, or 12 μg/ml of ZnO NPs or 12 μg/ml of ZnO NPs plus 5 mM of NAC for 6 h, respectively. The astrocytes were pretreated for 1 h with 5 mM of NAC before 6 h of co-exposure with ZnO NPs (12 μg/ml). The dot plots and the relative mean values have been obtained from a single representative experiment of three representative experiments that gave very similar results. (C) Effect of ZnO NPs on the expression of apoptosis-related proteins in cultured primary astrocytes. The cells were treated with 4, 8, or 12 μg/ml of ZnO NPs or 12 μg/ml of ZnO NPs plus 5 mM of NAC for 6 h or 12 μg/ml of ZnO NPs for 6, 12, or 24 h, respectively. The cells were collected to measure their protein expression levels (cleaved PARP, cleaved caspase-3, Bcl-2, Bax, and β-actin) as described in the ‘Materials and methods’ section. Data are presented as the mean ± SD of the three representative experiments. *p < 0.05, **p < 0.01, ***p < 0.001 vs. control. #p < 0.05, ##p < 0.01 vs. ZnO NPs (12 μg/ml).