Effects of electro-acupuncture on endotoxic shock-induced acute kidney injury in rabbits: relationship with Keap1-Nrf2/ARE signaling pathway

Abstract

Objective To evaluate the effects of electro-acupuncture (EA) at Zusanli and Shenshu acupoints on endotoxic shock-induced acute kidney injury (AKI) and the relationship with Keap1-Nrf2/ARE signaling pathway in rabbits.Methods Forty pathogen-free male New Zealand white rabbits,weighing 1.5-2.0 kg,were randomly divided into 4 groups randomly (n =10 each) using a random number table:control group (group C) ; endotoxic shock-induced AKI (group AKI) ; EA + endotoxin-induced AKI group (group EA) ; EA at non-acupoints + endotoxin-induced AKI group (group SEA).Endotoxic shock-induced AKI was induced with LPS 5 mg/kg (in 2 ml of normal saline) injected via the auricular vein.Electro-stimulation (2/15 Hz,0.2-0.6 ms,1-2 mA) of Zusanli and Shenshu acupoints was performed for 10 min once a day for 4 consecutive days,and the model was established on 5th day and then EA was continued until the animals were sacrificed in group EA.In group SEA,EA was performed at the points 5 mm lateral to the acupoints of Zusanli and Shenshu,and the other procedures were similar to those previously described in group EA.At 6 h of LPS,the urine was collected for determination of α1-microglobulin (α1-MG) concentrations.The animals were sacrificed and kidneys were removed for microscopic examination of the pathological changes which were also scored.Dry-wet weight method was used to measure water content in renal tissues.Nrf2 mRNA and HO-1 mRNA expression was detected using RT-PCR.The expression of Nrf2 total protein and nuclear protein and downstream HO-1 in renal tissues was determined by Western blot.Results Compared with group C,pathological scores,water content in renal tissues,and urinary α1-MG were significantly increased,and the expression of Nrf2 total protein and nuclear protein,HO-1,Nrf2 mRNA and HO-1 mRNA was up-regulated in AKI,EA and SEA groups.Compared with group EA,pathological scores,water content in renal tissues,and urinary α1-MG were significantly increased,and the expression of Nrf2 total protein and nuclear protein,HO-1,Nrf2 mRNA and HO-1 mRNA was down-regulated in AKI and SEA groups.There was no significant difference in each parameter between AKI and SEA groups.Conclusion EA at Zusanli and Shenshu can attenuate AKI induced by endotoxic shock in rabbits,and activation of keap1-Nrf2/ARE signaling pathway may be involved in the mechanism. Key words: Electric stimulation therapy ; POINT ST36 (ZUSANLI) ; POINT SL23 (SHENSHU) ; Endotoxemia ; Shock, septic ; Kidney failure, acute ; Nuclear factor erythroid 2-related factor2