Figure 5. Adiponectin protection against cytotoxicity of SH-SY5Y cells transfected with Swedish-APP (Sw-APP) mutant under oxidative stress.

(A) Percentage cytotoxicity of SH-SY5Y cells transfected with Sw-APP mutant under oxidase stress by different concentrations of hydrogen peroxide (H₂O₂) without and with pretreatment of adiponectin at 10 µg/ml expressed as fold of cytotoxicity relative to cytotoxicity without exposure to H₂O₂ (untreated, fold = 1) were shown on y-axis. In all three H₂O₂ concentrations, percentage cytotoxicity were significantly reduced with adiponectin pretreatment (p<0.05 for 200 µM H₂O₂, p<0.0001 for 400 µM H₂O₂ and p<0.05 for 800 µM H₂O₂). (−) ADN = without adiponectin pretreatment, (+) ADN = with adiponectin pretreatment. Results shown were mean values from 5 independent cultures, and compared by one-way ANOVA using Newman-Keuls multiple comparison test. (B) Using Sw-APP transfected SH-SY5Y cells with knockdown of AdipoR1 or AdipoR2 expression for the cytotoxicity experiments, it was observed that the protective effect of adiponectin against cytotoxicity under oxidative stress was preserved in control Sw-APP transfected SH-SY5Y cells without knockdown of AdipoR1 or AdipoR2 (scramble RNA+ADN+400 µM H₂O₂), but lost in cells with knockdown of AdipoR1 (AdipoR1 siRNA+ADN+400 µM H₂O₂) or AdipoR2 (AdipoR2 siRNA+ADN+400 µM H₂O₂) expression. This confirms that protective effect of adiponectin against cytotoxicity under oxidative stress in Sw-APP transfected SH-SY5Y cells required binding of adiponectin to its cell surface receptors AdipoR1 or AdipoR2. untreated = Sw-APP transfected SH-SY5Y cells without exposure to H₂O₂, 400 µM H₂O₂ = Sw-APP transfected SH-SY5Y cells exposed to 400 µM H₂O_2, ADN+400 µM H₂O₂ = Sw-APP transfected SH-SY5Y cells pretreated with adiponectin before exposure to 400 µM H₂O_2. Results shown were mean values from 3 independent cultures, and compared by one-way ANOVA using Newman-Keuls multiple comparison test.