Comparison Of In Vivo Protective Effect Of N-acetyl Cysteine And Dexamethasone In Lipopolysaccharide-induced Acute Lung Injury In Rats

Objective: The purpuse of this experiment is to study the method of reproduce the model of acute lung injury(ALI) in rats through Lipopolysaccharide(LPS) vein injection, study the protective effect and mechanism of N-acetyl cysteine(NAC) and Dexamethasone(Dex) in LPS induced ALI in rats. By comparing the protective effect of NAC and Dex in LPS induced ALI in rats, to provide a better clinical method in treating ALI.Methods: LPS(5mg/kg) was used to reproduce the model of ALI in rats. Thirty-two adult SD rats were randomly divided into four groups and there were eight rats in every group: control group(NS group);ALI model group(LPS group);NAC pretreative group(N&L group) and Dex pretreative group(D&L group). In the later two groups, NAC(200mg/kg) or Dex(70mg/kg) was injected intraperitoneally respectively one hour before LPS was given intravenously. Four hours after LPS was given, the rats were killed and the pathological manifestation of rats' lung was observed, the lung index was calculated, the intension of nuclear factor- K B(NF- K B) expression and inducible nitric oxide synthase(iNOS) expression of raf s lung was analyzed by the method of immunohistochemistry, and also the concentration of nitric oxide(NO) and malondialdehyde(MDA) in serum was detected.Result: There are obvious ALI pathological manifestation in LPS group rats' lung. Compared with the LPS group, the pathological manifestation of rats' lung was ameliorated and the evaluation of lung index, the expression of NF- K B and iNOS inraf s lung, the concentration of NO and MDA in serum were decreased significantly in N&L group and D&L group(P<0.05) and there were no significance in N&L group and D&L group(P>0.05).Conclusion: The method of reproducing the model of ALI in rats through LPS vein injection is good; NF- K B, iNOS in rats' lung and NO all take part in LPS induced ALI in rats, NAC or Dex can protect LPS induced ALI in rats and the possible mechanism is through inhibiting NF- K B in rats' lung, reduce iNOS in rats' lung and reduce NO in rats; Because there is no different protective effect in LPS induced ALI in rats between NAC and Dex. and considered the side-effects of Dex, it is promising to use NAC in the clinical treatment of ALI.