Role of activator protein-1 in up-regulation of heme oxygenase-1 expression during lipopolysaccharide-induced acute lung injury in rats

Abstract

Objective To evaluate the role of activator protein-1 (AP-1) in the up-regulation of heme oxygenase-1 (HO-1) expression during lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats.Methods Forty-eight healthy male Sprague-Dawley rats,weighing 200-220 g,aged 2.5-3.0 months,were randomly divided into 4 groups (n=12 each): normal control group (group C),ALI group,curcumin + ALI group (group Cur+ ALI),and curcumin group (group Cur).In groups C and ALI,normal saline 0.5 ml and LPS 10 mg/kg (0.5 ml) were injected intravenously,respectively,30 min after 0.1％ dimethyl sulfoxide (the vehicle for curcumin) 0.5 ml was injected intraperitoneally.In groups Cur+ ALl and Cur,curcumin 20 mg/kg (0.5 ml) was injected intraperitoneally,and 30 min later LPS 10 mg/kg and normal saline 0.5 ml were injected,respectively.The rats were then sacrificed at 6 h after injection of LPS.The lungs were removed for microscopic examination.The pathological changes of the lung were scored.The malondialdehyde (MDA) content,superoxide dismutase (SOD)activity and expression of HO-1,AP-1 and HO-1 mRNA in lung tissues were determined.Results Compared with group C,the pathological score and MDA content were significantly increased,the SOD activity was significantly decreased,and the expression of HO-1,AP-1 and HO-1 mRNA was up-regulated in groups ALl and Cur +AL(l) (P ＜ 0.05),and no significant change was found in the parameters mentioned above in group Cur (P ＞ 0.05).The pathological score and MDA content were significantly higher,and the SOD activity and expression of HO-1,AP-1 and HO-1 mRNA were significantly lower in group Cur + ALl than in group ALI(P ＜ 0.05).Conclusion Transcription factor AP-1 activation is involved in the up-regulation of HO-1 expression during LPS-induced ALI in rats. Key words: Activator protein-1; Endotoxemia; Heme oxygenase-1; Respiratory distress syndrome,adult