Figure 4.

Aβ oligomers increase intracellular ROS and stimulate caspase activation in human neuroblastoma cells. SH‐SY5Y cells were incubated for 24 h with buffer equivalent (VEH, vehicle) or 0.01 μM Aβ _1–42 oligomerization products (Aβ). (A) Intracellular ROS was evaluated using the DCFH‐DA probe. Treatment with 25 μM H₂O₂ served as a positive control. Results are expressed as the fold increase in intracellular ROS relative to the vehicle. Error bars indicate SEM, n = 14. (B) Caspase activation was evaluated via staining with FLICA reagent for detection of caspase‐1, caspase‐3, caspase‐4, caspase‐5, caspase‐6, caspase‐7, caspase‐8, and caspase‐9 (green) in conjunction with nuclear (Hoechst) staining (blue). Treatment with 1.5 U/μL TNF‐α served as a positive control. Scale bar represents 50 μm. Images are representative of 8–13 independent experiments. (C) Cellular caspase activation was determined via analysis of Hoechst and FLICA images using custom MATLAB functions that quantify the total number of cells and the number of caspase activated cells, respectively. Results are reported as the fraction of caspase activated cells. Error bars indicate SEM, n = 8–13. ^♦♦♦ P < 0.001 versus vehicle.