Effect of Nrf2/HO-1 Pathway on Electroacupuncture-induced Reduction of Lung Injury Induced by Limb Ischemia-reperfusion in Rabbits
WANG De-qiang, YU Jian-bo, KAN Yong-xing, et al.
Department of Anesthesiology, Dagang Hospital of Tianjin Binhai New Area, Tianjin (300270), China
Abstract:
Objective To observe the effect of nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway on electroacupuncture-induced reduction of lung injury induced by limb ischemia- reperfusion in rabbits. Methods Forty New Zealand white rabbits were randomly divided into 4 groups (n=10), such as Sham operation group, limb ischemia-reperfusion group, electrical acupoint stimulation group and all-trans retinoic acid group. Limb ischemia-reperfusion was induced by clamping bilateral femoral arteries for 3 h followed by 4 h reperfusion. Bilateral electroacupuncture stimulation of Zusanli and Feishu acupoints was performed with disperse-dense wave 2/15 Hz for 30 min once daily for 4 d before establishment of the model and during the course of establishment of the model in electrical acupoint stimulation group and all-trans retinoic acid group. At 30 min before establishment of the model, Nrf2 inhibitor all-trans retinoic acid (7 mg/kg) was injected intraperitoneally in all-trans retinoic acid group. The rabbits were sacrificed at 4 h of reperfusion and the lungs were removed for microscopic examination and determination of lung injury scores, wet to dry weight ratio (W/D), malondialdehyde (MDA) contents, superoxide dismutase (SOD) activities, and expression of Nrf2 total protein, nucleoprotein and HO-1 protein by Western blotting. Results The lung W/D ratio after 4 h reperfusion in limb ischemia-reperfusion group, electrical acupoint stimulation group and all-trans retinoic acid group were 6.42±1.00, 4.45±0.68 and 7.08±1.12, respectively. The lung injury scores at 4 h in above three groups were 5.43±0.82, 4.03±0.56 and 6.21±0.75, respectively. Both lung W/D ratio and lung injury scores in above three groups were significantly higher than those of Sham operation group. MDA contents [(4.82±0.51) nmol/mg, (3.56±0.45) nmol/mg and (5.18±0.47) nmol/mg] in limb ischemia-reperfusion group, electrical acupoint stimulation group and all-trans retinoic acid group were significantly increased compared with Sham operation group [(2.10±0.23) nmol/mg, P<0.05]. The SOD activities [(50.6±6.3) U/mg, (63.1±7.7) U/mg and (47.2±5.6) U/mg] in limb ischemia-reperfusion group, electrical acupoint stimulation group and all-trans retinoic acid group were significantly decreased compared with Sham operation group [(72.6±6.3) U/mg, P<0.05]. The expression of Nrf2 total protein, nucleoprotein and HO-1 protein in above three groups were significantly up-regulated compared with Sham operation group (P<0.05). Compared with limb ischemia-reperfusion group, lung W/D ratio, lung injury scores and MDA contents were significantly decreased, while SOD activities, expression of Nrf2 total protein, nucleoprotein and HO-1 protein were significantly increased in electrical acupoint stimulation group. Compared with electrical acupoint stimulation group, the lung W/D ratio, lung injury scores and MDA contents were significantly increased, while SOD activities, expression of Nrf2 total protein, nucleoprotein and HO-1 protein were significantly decreased in all-trans retinoic acid group. Conclusion Activation of Nrf2/HO-1 signaling pathway is involved in electroacupuncture-induced reduction of lung injury induced by limb ischemia-reperfusion in rabbits.
