Abstract: Aim To assess the effect and mechanism of Nacetylcy steine (NAC, antioxidant) on nuclear factor- κB (NF-κB) in lung tissue and bronhial alveolar lavage fluid (BALF) of rats undergoing acute and chronic smoking. Methods All Wistar rats were divided randomly into three groups: control group, smoking group and intervention group. The latter two groups were applied to observing NF-κB expression during different periods (1, 2, 7, 14, 60d). Western-Blot assay was used to analyze the activation of NF-κB. Results The first and second day the expression of NF-κB in lung tissue (36.9 ±8.1 and 36.9 ±8.0) and in BA LF(24.0 ±6.1 and 21.2 ± 5.8) rose significantly comparing with that in the control groups (7.3 ±2.8 and 5.7 ±2.6) respectively (P <0.01), but fell to the normal range of control at the seventh, fourteenth and sixtith days of smoking. NAC significantly inhibited the higher NF-κB expression comparing with that in the related control smoking groups, but not inhibited the normal NF-κB expression in the rest groups. Conclusion NAC, through inhibiting activation of NF-κB during the early smoking stage and further blocking the activation of pro-inflammatory cytokines, may play a role in pathogenesis of airway inflammation of COPD.

Key words: N-acetylcysteine, nuclear factor-κB, smoking, rats