Objective To explore the changes of nuclear factor-κB(NF-κB) activity,TNF-α,IL-1β and IL-10 contents in the lung tissue of rabbit with seawater drowning-induced acute lung injury(SWD-ALI) and the effects of dexamethasone on the changes.Methods Forty-two New Zealand white rabbits were randomly allocated to control group(C group,n = 18),seawater drowning group(S group,n = 12) and dexamethasone treatment group(D group,n = 12).The drowning model was established by instilling seawater(2 ml/kg body weight) into the endotracheal catheter of animals,then the rabbits received arterial injection of dexamethasone(D group,1 mg/kg body weight) or 2 ml normal saline(S group).Blood gas analysis was done at predefined time points.The lung wet to dry weight ratio(W/D) and lung permeability index(LPI) were calculated.The activity of NF-κB was analyzed by non-radioactive electrophoretic mobility shift assay(EMSA).The contents of TNF-α,IL-1β and IL-10 were detected by ELISA.Meanwhile,the pathology changes of lung tissues were detected by H-E staining,and the semi-quantitative lung pathologic scores(LPS) was also calculated.Results The lung of rabbits in S group was obviously enlarged and had more severe edema and congestion compared with C group;furthermore,histopathologic findings indicated inflammatory cell infiltration and other pathologic signs of ALI;the oxygenation index(PaO2 /FiO2) reached the bottom at 0.5 h and did not elevate to more than 300 mmHg(1 mmHg = 0.133 kPa) until 6 h.The largest W/D ratio appeared at 3 h after seawater drowning,and the highest LPI and LPS appeared at 6 h;and NF-κB activity and the contents of TNF-α,IL-1β and IL-10 in lung tissues were significantly higher in S group than in C group(P 0.05,P 0.01).The pathological changes of lung in the rabbits of D group were improved compared with S group but worse than those of group C.The W/D ratio,lung permeability index,and lung pathological score in D group were lower than those of the S group;and the oxygenation index was greatly improved 6 h after seawater drowning.NF-κB activity and the contents of TNF-α,IL-1β and IL-10 in lung tissues were significantly lower than those of the S group(P 0.05,P 0.01).Conclusion Dexamethasone can inhibit the activity of NF-κB and the expression of TNF-α,IL-1β and IL-10 in the lung tissue of rabbits with SWD-ALI and relieve the inflammatory responses and pathological changes.