Oregano Essential Oil Induces SOD1 and GSH Expression through Nrf2 Activation and Alleviates Hydrogen Peroxide-Induced Oxidative Damage in IPEC-J2 Cells

Figure 5

Effects of oregano essential oil (OEO) on g-glutamylcysteine ligase (GCLM, GCLC) and Cu/Zn-superoxide dismutase (SOD1) expression in nuclear factor-erythroid 2-related factor-2 (Nrf2) knockdown IPEC-J2 cells. (a, b) IPEC-J2 cells were treated with Nrf2 siRNA or control siRNA and incubated for 24 h. (a) Nrf2 mRNA expression was quantitated and normalized as for Figure 3(a). (b) Whole-cell lysates were subjected to western blotting. (c–f) IPEC-J2 cells were transfected with siRNA against Nrf2 or control siRNA. After 24 h, the cells were incubated with OEO (2.5–10 μg/mL) for an additional 12 h. Nrf2, GCLC, GCLM, and SOD1 mRNA expression levels were measured quantitatively using real-time RT-PCR. (g-h) IPEC-J2 cells were transfected with siRNA against Nrf2 or control siRNA. After 24 h, the cells were incubated with OEO 10 μg/mL for an additional 24 h. Nrf2, Kelch-like ECH-associated protein 1 (Keap1), GCLC, GCLM, and SOD1 were estimated by western blot. (i) Effect of OEO on intracellular glutathione (GSH) content in Nrf2 knockdown IPEC-J2 cells. OEO (2.5–10 μg/mL) was applied as described for Figure 3(j), and intracellular GSH content was measured. (j) Effect of OEO on intracellular SOD1 content in Nrf2 knockdown IPEC-J2 cells. OEO (2.5–10 μg/mL) was applied as described for Figure 3(k), and intracellular SOD1 content was measured. Values represent means ± SEM, . , , and , compared with control cells treated with control siRNA; , compared with corresponding cells treated with control siRNA. Means without a common letter differ, .

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