The Expression Changes Of SIRT1 In The Lung Tissue Of Rats In Response To Oxidative Stress Induced By PM_2.5 And The Interventional Effect Of N-acetyl-l-cysteine

Obstructive: Fine particulate matter(PM_2.5) is currently the main pollutants of air pollution which causes serious damage to the human body. Oxidative stress is considered to play a important role in many diseases associate with exposure to PM_2.5. Oxidative stress represents the imbalance between oxidation and anti-oxidation system that causes a series of physiological and pathological processes. SIRT1 is a kind of NAD-dependent histone and non-histone deacetylases of sirtuins protein family.Many studies confirmed that SIRT1 has a significant effect in resistance to oxidative stress by regulating the acetylation level of histone and non-histone. N-acetylcysteine as a sulfhydryl-containing compounds has been widely used in clinical treatment because of its antioxidant function. This article is to study the expression change of SIRT1 in the lung tissue of rats in the process of oxidative stress induced by PM_2.5, explore the anti-oxidative mechanism of SIRT1 and the interventional effect of N-acetyl-l-cysteine.Methods:1 Model building: A total of 24 healthy male Sprague-Dawdley? SD? rats were divided randomly into 3 groups, namely PM_2.5 group,PM_2.5+ NAC group, Filtered air group?the control group?.The rats were executed after 12 weeks. The PM_2.5 group rats were exposed to ambient air of Shijiazhuang city; PM_2.5+NAC group rats were exposed to ambient air of Shijiazhuang city and were given by gavage once a day with NAC 150mg/kg. The control group rats inhaled filtered clean air indoor.2 The pathological changes of lung tissue were observed under microscope with hematoxylin-eosin?HE? staining.3 The malondialdehyde?MDA? content of rats pulmonary tissue homogenate were measured by the thiobarbituric acid method?TBA?.4 The gene expressional level of MnSOD and SIRT as well as FoxO3 a in lungs were measured by reverse transcriptase polymerase chain reaction?RT-PCR?.5 The protein expressional level of MnSOD and SIRT as well as FoxO3 a in lungs were measured by Western blot.6 The SIRT1 enzymatic activity was detected by active quantitative colorimetric method.Results:1 The general condition of rats: Rats in the control group had good mental state, reacted quickly and had smooth fur. They ate and drank as usual. Rats in the PM_2.5 group were curled up, reacted a bit slowly but ate and drank as usual. Rats in the PM_2.5+NAC group acted like the control group.2 The pathological change of rats lung tissue:Compared with the control group,the alveolar wall got thinner, alveolar interval was slightly thicker and inflammatory cells were seen infiltrated in the pulmonary interstitial and alveolar space. The inflammatory level of the PM_2.5+NAC was between the control group and the PM_2.5 group.3 The content change of MDA and MnSOD in rats lung tissue: Compared with the control group, MDA in the lung tissue of PM_2.5 group was high?1.52±0.11 vs 0.99±0.07,P<0.01?,but was decreased after NAC intervention?1.30±0.19 vs 1.52±0.11,P<0.01?;Expression of Mn SOD protein and MnSOD mRNA were decreased significantly in the PM_2.5 group compared with the control group? 0.98±0.06vs1.41±0.04,0.75±0.09vs1.45±0.03,P<0.01?,but their expression level could get higher than before after NAC intervention?1.21±0.01 vs0.98±0.06,1.29±0.04 vs 0.75±0.09,P <0.01?.4 Application of RT-PCR analysis SIRT1 and FoxO3 a mRNA expression in the lung tissue: Compared with the control group,expression of SIRT1 and FoxO3 a m RNA were decreased in PM_2.5 group?1.04±0.04 vs1.83±0.08,0.89±0.09vs1.38±0.09,P<0.01?,but they increased significantly after NAC intervention?1.52±0.04 vs1.04±0.04,1.21±0.07 vs 0.89±0.09,P <0.01?.5 Application of Western blot analysis SIRT1 and FoxO3 a protein expression in the lung tissue: Compared with the control group,expression of SIRT1 and FoxO3 a protein were decreased in PM_2.5 group?0.51±0.05 vs1.43±0.04,0.42±0.09vs1.33±0.09,P<0.01?,but they increased significantly after NAC intervention?1.08±0.05 vs0.51±0.05,1.17±0.10 vs 0.42±0.09,P <0.01?.6 The change of SIRT1 enzymatic activity in the rats lung tissue: The SIRT1 enzymatic activity in the lung tissue was lower in PM_2.5 group than the control group?0.31±0.08 vs 0.96±0.37,P<0.01?, but it increased after NAC intervention?0.63±0.05 vs 0.31±0.08,P<0.01?.Conclusions:1 The differences of SIRT1 expression in the rat lung tissue in different groups may play an important role in the process of oxidative injury induced by PM_2.5.2 SIRT1 may protect lung tissue from oxidative injury that PM_2.5 caused by raising the FoxO3 a expression level and enhance the expression of downstream factor MnSOD.3 NAC plays a protective role in the process of oxidative injury induced by PM_2.5 and the mechanism may be related to its activation effect of SIRT1.