Role Of PKC-?-Nrf2/HO-1 Signaling Pathway In Electroacpuncture During Acute Lung Injury Induced By Endotoxic Shock In Rabbits

Background: Acute lung injury(ALI) or acute respiratory distress syndrome(ARDS) can be induced by Endotoxic shock, which could lead to multiple organ failure and has a high mortality rate.It has been confirmed that lung can be protect by stimulation of electro-acupuncture to Zusanli and Feishu.In previous study, we also found that Activation of Nrf2-ARE pathway is the regulatory mechanism of the body adapting to the ALI induced by endotoxic shock in rabbits. Protein kinase C(PKC) is a family of Ser/Thr kinase which generally exist in tissues and cells of body.Objective: To probe into the effect of PKC-? on electroacupuncture upregulating Nfr2/HO-1 pathway of acute lung injury induced by endotoxic shock in rabbits.Methods: Eighty healthy male New Zealand white rabbits were randomly divided into 8 groups(n=10 each): normal control group(Group C), endotoxic acute lung injury group(Group L), electroacupuncture at acupoints+L group(Group EL), electroacupuncture at non-acupoints+L group(Group SEL),electric acupuncture+ endotoxic acute lung injury group+PKC blocker chelerythrine(Group ELC), chelerythrine(Group Che),chelerythrine+L group(Group LC),and DMSO group(Group E).Zusanli, Neiguan and Feishu acupuncture points were chosen under guide of animal acupuncture atlasdeveloped by Chinese Acupuncture Association in the EL group and ELC group. A disposable sterile acupuncture needle was punctured in for 5-7mm and twirled for 1 minute, then connected to G6805-1A Low-frequency electronic pulse therapeutic instrument for stimulation,lasting for 30min/session, 1 session/day, 5 consecutive days. Same way applied to SEL group with acupuncture points at 0.5cm beside the point. Chelerythine(5mg/kg diluted in 0.5ml 0.1% DMSO) was injected into the marginal ear vessels of the rabbits in Che,LC and ELC groups,while 0.5 ml 0.1%DMSO was used in E group and the equal volume saline in other groups.30 min later, endotoxic acute lung injury were produced by injection of lipopolysaccharide(LPS)(5 mg/kg diluted in 2ml saline) via auricular vein in L, EL, SEL,LC and ELC groups, while other groups with same amount of normal saline. Endotoxic shock model was confirmed when there was an initial 25% decrease in mean arterial pressure( MAP). The rabbits would be sacrificed by bloodletting at 6h after LPS or normal saline administration. The pulmonary tissues were removed for microscopic examination and pathological injury scores.The wet/dry lung weight ratio(W/D) was computed.The malondialdehyde(MDA) contents and superoxide dismutase(SOD) activity in the pulmonary tissue were inspected,and the expression of HO-1protein,PKC-? protein,Nrf2 m RNA,HO-1m RNA,Nrf2 nucleoprotein and total protein in lung tissues was ascertained.Results: Compared with group C, the activities of SOD,the expression of Nrf2 nucleoprotein,total protein, HO-1protein, HO-1m RNA,Nrf2 m RNA and PKC-? protein were decreased, while the lung injury scores, W/D ratio, MDA content were increased in L, EL,SEL,LC and ELC groups(P<0.05). No statistical significances were found in Che and E groups(P>0.05).Compared with group L, the activities of SOD, the expression of Nrf2 nucleoprotein,total protein, HO-1protein, HO-1m RNA,Nrf2 m RNA and PKC-? protein were increased, while the lung injury scores, W/D ratio, MDA content were decreased in group EL(P<0.05), the activities of SOD, the expression of Nrf2 nucleoprotein,total protein, HO-1protein, HO-1m RNA,Nrf2 m RNA and PKC-? protein were decresed while the lung injury scores, W/D ratio, MDA content were increased in LC and ELC groups(P<0.05).No statistical significances were found in SEL group(P>0.05).Compared with EL group, the activities of SOD, the expression of Nrf2 nucleoprotein,total protein, HO-1protein, HO-1m RNA,Nrf2 m RNA and PKC-? protein were decreased while the lung injury scores, W/D ratio, MDA content were increasedin SEL and ELC groups(P<0.05). Compared with LC group, the activities of SOD, the expression of Nrf2 nucleoprotein,total protein, HO-1protein, HO-1m RNA,Nrf2 m RNA and PKC-? protein were increased while the lung injury scores, W/D ratio, MDA content were decreased in group LC(P<0.05).Conclusion: In summary, electroacupuncture at Zusanli, Neiguan and Feishu could alleviate lung injury induced by endotoxic shock in rabbits through the activation of PKC-?-Nrf2/ARE pathway.