University of Guilan Caspian Journal of Environmental Sciences 1735-3033 2023 07 01 Effects of the air pollution on the decreased P53, Nrf2 and HO-1 protein levels along with tissue damage caused by oxidative stress in the lung of rat as an animal model 1 8 6825 10.22124/cjes.2023.6825 EN Mahdi Farhadi Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Pejman Mortazavi Department of Pathobiology, Science and Research Branch, Islamic Azad University, Tehran, Iran Saeed Motesaddi Zarandi Department of Environmental Health Engineering, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran Akram Eidi Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Journal Article 2023 07 01 Air pollution is associated with respiratory pathologies, and exposure to airborne particles with an aerodynamic diameter of 2.5 microns (PM_2.5) is a significant risk factor for respiratory patients. This study aimed to investigate the effects of PM_2.5 exposures on lung tissue pathology and the function of antioxidant enzymes in a rat animal model. The animals were exposed to PM_2.5for two different periods: 3 and 6 months, with a frequency of 4 days per week and a duration of 5 hours (from 9.00 am to 14.00 pm) per day. The activity of antioxidant enzymes, as well as lung histology and the protein expression of p53, Nrf2, and HO-1, were assessed in the lung tissue of the exposed rats. The results revealed a significant increase in malondialdehyde (MDA) levels and a significant decrease in antioxidant enzymes (CAT, SOD, and GPx) in the animals exposed to PM_2.5. Moreover, a noticeable reduction in the protein levels of p53, Nrf2, and HO-1 was observed in the lung tissues of the rats after PM_2.5 exposure, which was accompanied by pathological changes. In conclusion, PM_2.5 exposure leads to severe damage to lung tissue by reducing the activity of antioxidant enzymes and inducing oxidative stress through the activation of Nrf2 and P53 signalling pathways. https://cjes.guilan.ac.ir/article_6825_fcfbbea77191256507c0397a9dc58ff9.pdf