Role of activator protein-1 in electro-acupuncture-induced up-regulation of heme oxygenase-1 expression in lung tissues in a rabbit model of endotoxic shock

Abstract

Objective To evaluate the role of activator protein-1 （AP-1 ） in electro-acupuncture （EA ）-induced up-regulation of heme oxygenase-1 （HO-1 ） expression in lung tissues in a rabbit model of endotoxic shock .Methods Seventy healthy male New Zealand white rabbits ,aged 2 months ,weighing 1.5-2.0 kg ,were randomly divided into 7 groups （ n=10 each ） using a random number table ：normal control group （group C ） , endotoxic shock-induced acute lung injury （ALI ） group （group ALI ） , EA ＋ ALI group （group EL ） , non-acupoint＋EA＋ ALI group （group NEL ） , curcumin （HO-1 inhibitor ） group （group Cur ） , dimethyl sulfoxide group （group D ） ,and EA＋ALI＋curcumin group （group ELC ） .Bilateral 15 min EA stimulation of Zusanli and＆nbsp;Feishu （according to atlas of animals acupoints ） was performed （frequency 15Hz ） once a day for 5 consecutive days before lipopolysaccharide （LPS ） administration in EL and ELC groups ,while in group NEL ,EA stimulation was performed at non-acupoints located 0.5 cm lateral to Zusanli and Feishu acupoints with the same parameters . The animals were anesthetized with urethane and tracheostomized .The animals kept spontaneous breathing .Right internal carotid artery was cannulated for blood pressure monitoring . Ear vein was cannulated for drug administration .At 5 days after EA stimulation ,curcumin 25 mg/kg （in 0.5 ml of 0.1% dimethyl sulfoxide ） was injected in Cur and ELC groups ,0.1% dimethyl sulfoxide 0.5 ml was injected in D group ,and the equal volume of normal saline was given in the other groups .LPS 5 mg/kg （in 2 ml of 0.9% normal saline ） was injected intravenously at 30 min after administration in ALI ,EL ,NEL and ELC groups ,while the equal volume of normal saline was given in the other three groups .Endotoxic shock was confirmed by decrease in mean arterial pressure to 75% of the baseline value within 2 h after LPS injection .Blood samples were collected from the common carotid artery at 6 h after LPS or normal saline administration and the rabbits were then sacrificed .The lungs were removed for microscopic examination and the pathological changes were scored .The wet/dry lung weight ratio （W/D ratio ） was calculated .The malondialdehyde （MDA ） content and superoxide dismutase （SOD ） activity in lung tissues were detected ,and the expression of HO-1 mRNA ,HO-1 ,c-Jun mRNA and c-Jun in lung tissues was determined by Western blot .Results Compared with group C ,the pathological score ,W/D ratio and MDA content were significantly increased ,and the SOD activity was decreased in ALI ,EL ,NEL and ELC groups ,the expression of HO-1 mRNA ,HO-1 ,c-Jun mRNA and c-Jun was up-regulated in groups ALI ,EL and NEL （ P0.05） .There was no significant difference in the parameters mentioned above between Cur and D groups （ P〉0.05 ） .Compared with group ALI ,the pathological score ,W/D ratio and MDA content were significantly decreased ,and SOD activity was increased ,and the expression of HO-1 mRNA and HO-1 was up-regulated in EL and ELC groups （ P0.05） .The pathological score ,W/D ratio and MDA content were significantly higher ,and the SOD activity and expression of HO-1 mRNA ,HO-1 ,c-Jun mRNA and c-Jun were lower in group ELC than in group EL （ P〈0.05） .Conclusion EA up-regulates HO-1 expression through activating AP-1 during endotoxic shock-induced ALI in rabbits ,thus protecting the lung . Key words: Transcription factor AP-1; Electric stimulation therapy; Shock,septic; Lung; Heme oxygenase-1