Effects of electroacupuncture on mitochondrial fusion-fission during endotoxin-induced acute lung injury in rabbits

Abstract

Objective To evaluate the effect of electroacupuncture (EA) on mitochondrial fusion-fission during endotoxin-induced acute lung injury (ALI) in rabbits. Methods Sixty clean-grade New Zealand white rabbits, aged 2 months, weighing 1.5-2.0 kg, were divided into 4 groups (n=15 each) using a random number table: control group (group C), ALI group, EA at non-acupoint plus ALI group (group SEAM+ ALI) and EA at acupoint plus ALI group (group EAM+ ALI). Endotoxin-induced ALI was induced by injecting lipopolysaccharide 5 mg/kg (in 2 ml of 0.9% normal saline) via the auricular vein in ALI, SEAM+ ALI and EAM+ ALI groups.At 4, 3, 2 and 1 days and 30 min before lipopolysaccharide injection, bilateral Zusanli (ST36) and Feishu (BL13) acupoints were stimulated with an electric stimulator for 30 min in group EAM+ ALI, and EA was performed for 30 min at the points 1 cm lateral to the acupoints of Zusanli and Feishu in group SEAM+ ALI.The animals were sacrificed at 6 h after lipopolysaccharide injection and the lungs were removed for microscopic examination of the pathological changes (with a light microscope) and mitochondrial ultrastructure (with an electron microscope) and for determination of ROS and ATP contents and expression of Mfn1, Mfn2, optic atrophy 1(OPA1) and dynamin-related protein 1(Drp1) protein and mRNA in lung tissues (by real-time polymerase chain reaction or Western blot). Results Compared with group C, ATP content was significantly decreased, ROS content was increased, the expression of Mfn1, Mfn2 and OPA1 protein and mRNA was down-regulated, and the expression of Drp1 protein and mRNA was up-regulated in ALI, SEAM+ ALI and EAM+ ALI groups (P<0.05). Compared with group ALI, ATP content was significantly increased, the expression of Mfn1, Mfn2 and OPA1 protein and mRNA was up-regulated, and the expression of Drp1 protein and mRNA was down-regulated in SEAM+ ALI and EAM+ ALI groups, and ROS content was decreased in group EAM+ ALI (P<0.05). Compared with group SEAM+ ALI, ATP content was significantly increased, ROS content was decreased, the expression of Mfn1, Mfn2 and OPA1 protein and mRNA was up-regulated, and the expression of Drp1 protein and mRNA was down-regulated in group EAM+ ALI (P<0.05). Conclusion The mechanism by which EA mitigates endotoxin-induced ALI may be related to promoting mitochondrial fusion and inhibiting mitochondrial fission in rabbits. Key words: Electric stimulation therapy; Shock, septic; Respiratory distress syndrome, adult; Mitochondrial fusion; Mitochondrial fission