Figure 7.

Catalpol activated Keap1/Nrf2/ARE pathway in H₂O₂-treated RPE cells. (a and b) ARPE-19 cells were pretreated with or without catalpol (10, 20 and 40 μM) for 24 h, and then treated with 400 μM H₂O₂ for 6 h. The expressions of HO-1, NQO1, Keap1, Total-Nrf2 and Nuclear-Nrf2 were measured with Western blot assay. Histone H3 was used as an internal control for nucleoprotein, while β-actin was used as an internal control for total protein. (c) The effect of catalpol on the formation of Keap1/Nrf2 complex was determined using co-immunoprecipitation assay. (d) Treatment with ML385, a Nrf2 inhibitor, blocked the antioxidant protective effects of catalpol on increases in the expression of Nrf2 protein in H₂O₂-treated ARPE-19 cells. (e) Changes in gene expression of NQO1 were assayed with qRT-PCR. Data are presented as mean ± S.D. of three independent experiments (* p < 0.05 vs. control group, # p < 0.05 vs. H₂O₂ (400 μM)-treated group).