en بیوشیمی Biochemistry مقالات اصلی Original Article <strong><em>Background:</em></strong> Tobacco use is responsible for millions of preventable deaths due to cancer. Nicotine, an&nbsp;alkaloid chemical found in tobacco was proved to cause chronic inflammation and oxidative stress. The&nbsp;transcription factor STAT1 induces the expression of many proinflammatory genes and has been suggested&nbsp;to be a target for anti-inflammatory therapeutics. The following study investigated the effect of Nicotine on&nbsp;STAT1 pathway and oxidative stress in rat lung tissue.&nbsp;<br> <br> <strong><em>Methods:</em></strong> Thirty rats were divided into 3 groups; group I considered as control, group II; its rats were&nbsp;daily injected with Nicotine at a dose of 0.4 mg/100 gm body for 8 successive weeks and group III;&nbsp;its rats were daily injected with Nicotine as group II, but the injection was stopped for another 4<br> weeks. STAT1&alpha; protein was assessed by immunohistochemistry, COX-2 and iNOS genes expression&nbsp;were evaluated by real time PCR and thiobarbituric acid reactive substances (TBARS) and total thiols&nbsp;were measured using spectrophotometric methods in the lung tissues of the rats.<br> <br> <strong><em>Results:</em></strong> The results of the study revealed that group II rats had the highest expression of STAT1&alpha; protein&nbsp;and COX-2 and iNOS genes and oxidative stress in their lung tissues. Nicotine cessation for 4 weeks&nbsp;caused a marked reduction in the expression of STAT1&alpha; protein, COX-2 and iNOS genes and oxidative&nbsp;stress.<br> <br> <em><strong>Conclusions:</strong></em> Induction of STAT1 pathway and the increase in oxidative stress may be the&nbsp;mechanisms through which Nicotine may induce its harmful effects. COX-2, iNOS, Nicotine, Oxidative stress, STAT1. 429 436 http://rbmb.net/browse.php?a_code=A-10-469-2&slc_lang=en&sid=1 Aida Abdeen Mahmoud aida_mahmoud@med.sohag.edu.eg. 100319475328460012547 100319475328460012547 Yes Department of Medical Biochemistry, Faculty of Medicine, Sohag University, Egypt. Hekmat Abdel-Aziz 100319475328460012548 100319475328460012548 No Department of Medical Histology, Sohag University, Egypt and of Mohamed Elbadr 100319475328460012549 100319475328460012549 No Department of Medical Pharmacology, Faculty of Medicine, Assiut University, Egypt. Hala ELBadre 100319475328460012550 100319475328460012550 No Department of Medical Biochemistry, Faculty of Medicine, Assiut University, Egypt.