FIG. 8.

Aβ does not cause astrocytic cell death but impairs the mitochondrial activity in a dose-dependent manner. (a) After stimulation with Aβ (50 μM; 25–35) or t-BuOOH (800 μM), the extent of astrocytic apoptosis was determined using the TUNEL assay. To permit quantitative analysis, nuclei were stained with Hoechst stain (excitation 365 nm, emission 480 nm). Red and green colors show staining for nuclei and apoptotic cells respectively. Merge represents the overlap of red and green; BF denotes bright-field contrast enhancement of the merged image. (b) After addition of different concentrations of Aβ (25–35, acute or repeated) stimulation for ∼20 h, cells were washed with phosphate-buffered saline, and incubated with MTT dye (0.5 mg/ml) for 2 h at 37°C, followed by washing in phosphate-buffered saline, dissolving in dimethyl sulfoxide, and reading the optical density at 553 nm. (a) shows representative data from two independent experiments. (b) shows data as mean±SD from 3 independent experiments each performed in triplicate on different batches of cells. *p≤0.05, **p≤0.01, ns=not significant. TUNEL, terminal deoxynucleotidyl transferase-dUTP nick end labeling.