Effects of N-acetylcysteine in lipopolysaccharide-induced acute lung injury in the rat: Treatment after acute lung injury

Introduction: As it has been known that N-Acetylcysteine (NAC) which is a free radical scavenger and antioxidant reduces acute lung injury of rats stimulated by endotoxin, studies on NAC are being executed recently as a way of treatments of lung injuries. This study was to elucidate effect of NAC in LPS-induced acute lung injury in rats. Methods: Six weeks old SD rats were divided into 4 groups (group 1: saline, 2: NAC, group 3: LPS, group 4: LPS+NAC). LPS was intravenously injected at the rate of 5mg/kg. NAC of 20mg/kg was injected into abdominal cavity 3, 6 and 12 hours after the injection of LPS. BAL fluids and lung tissues were obtained from individual rats. Using 100mg of lung tissues, the levels of NF-kB and lipid peroxidation (LPO) were measured. Results: Neutrophilic inflammations of the lung tissues and BAL fluids were the most severe in the LPS group. The amounts of NF-kB in the group 3 (0.32±0.23 ng/μl) showed statistically significant differences compared with the group 1 (0.16±0.12 ng/μl), 2 (0.16±0.12 ng/μl) (p<0.001) and 4 (0.25±0.19 ng/μl) (p<0.05). The amounts of LPO in the group 3 (15.29±3.76 nmol/ml) showed statistically significant differences compared with the group 1 (4.35±4.27 nmol/ml), 2 (4.99±5.06 nmol/ml) (p<0.001) and 4 (7.65±6.24 nmol/ml) (p<0.01). Conclusion: N-Acetylcysteine has a protective effect to reduce acute lung injury stimulated by endotoxin and it is considered that the mechanism appears in relation to neutrophils that are mainly involved in lung injuries.