Oxygen Concentration and Oxidative Stress Modulate the Influence of Alzheimer’s Disease Aβ_1–42 Peptide on Human Cells

Figure 4

Intracellular ROS level in SH-SY5Y cells. (a) Shift in the fluorescence signal of 27-dihydrofluorescein in comparison to the signal of the positive control (H₂O₂-treated cells) and to the nontreated cells detected 18 h after irradiation and 24 h after amyloid beta treatment or combination of both in SH-SY5Y cells depending on the oxygen concentration (21% and 5% O₂, resp.; results from single measurements by flow cytometry were plotted). (b) Generally higher (~1.5-fold) ROS level was detected in cells cultivated at 21% O₂ compared to 5% O₂. A slight (~1.1-fold) increase of ROS level after Aβ peptide treatment at 21% O₂ and about 1.3-fold at 5% O₂. A significant (1.8-fold) increase of ROS level after irradiation at 5% O₂ only and after irradiation of Aβ peptide-treated cells at both 21% (~1.2-fold) and 5% O₂ (~1.4-fold). Samples were measured at least in duplicates () in at least three () independent experiments, and relative fluorescence values are presented as percentages (%) of the fluorescence value of the H₂O₂ control (100%). Mean ± SEM analyzed by two-way ANOVA with Tukey’s test. (, , and ).

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