Protective effect of Nrf2/NF-κB signal pathway on the rats with ischemic optic neuropathy in hyperbaric oxygen treatment

Objective To observe the effect of hyperbaric oxygen (HBO) on oxidative stress and apoptosis in the rats with ischemic optic neuropathy. Methods Thirty Sprague-Dawley (SD) rats were randomly divided into 3 groups: the sham surgery group, the model group and the HBO group, each consisting of 10 rats. The sham surgery group just received surgery, but without ischemic optic neuropathy. The rats in the model and HBO groups were treated with ischemic optic neuropathy, but the HBO group received HBO therapy after surgery. The expression levels of Nrf2 mRNA and NF-κB mRNA in the optic nerve were detected by real-time fluorescence quantitative PCR, the expression levels of Nrf2 nucleoprotein and NF-κB protein in the optic nerve were identified by Western-blotting and the levels of blood peroxide (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of various groups were detected by ELISA. Results The expression levels of Nrf2 mRNA, Nrf2 nucleoprotein, NF-κB mRNA and NF-κB protein in the optic nerve of the model group were all higher than those of the sham surgery group, and there was statistical significance when comparisons were made between them (P<0.05). The activity of CAT, SOD and GSH-Px in the model group was lower than that in the sham surgery group, and statistical significance could also be seen when comparisons were made between them (P<0.05). The expression levels of Nrf2 mRNA, Nrf2 nucleoprotein, and the activity of CAT, SOD and GSH-Px in the HBO group were all significantly higher than those of the model group, and statistical significance could also be noted when comparisons were made between them (P<0.05). The expression levels of NF-κB mRNA and NF-κB in the HBO group were significantly lower than those of the model group, and statistical significance could also be found when comparisons were made between them (P<0.05). Conclusions HBO therapy could up-regulate the expression level of Nrf2 nucleoprotein, increase the activity of CAT, SOD and GSH-Px, inhibit the expression level of NF-κB and improve the capacity of anti-oxygenation and anti-apoptosis in the rats with ischemic optic neuropathy. Key words: Ischemic optic neuropathy; Hyperbaric oxygen; Nrf2; Oxidative stress