Effect of Sulfur Dioxide Inhalation on CYP2B1/2 and CYP2E1 in Rat Liver and Lung

Abstract

Sulfur dioxide (SO₂) is a ubiquitous air pollutant, present in low concentrations in the urban air and in higher concentrations in the working environment. In this study, we investigated the effects of inhaled SO₂ on the O-dealkylase of pentoxyresorufin (PROD) and p-nitrophenol hydroxylases (p-NP) activities and mRNA levels of CYP2B1/2 and CYP2E1 in the lung and liver of Wistar rats. Male Wistar rats were housed in exposure chambers and treated with 14.11 ± 1.53, 28.36 ± 2.12, and 56.25 ± 4.28 mg /m³ SO₂ for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. The mRNAs of CYP2B1/2 and -2E1 were analyzed in livers and lungs by using reverse-transcription polymerase chain reaction (RT-PCR). Our results showed that the PROD activities and mRNA of CYP2B1/2 were decreased in livers and lungs of rats exposed to SO₂. The p-NP activities and mRNA of CYP2E1 were decreased in lungs but not in livers of rats exposed to SO₂. Total liver microsomal cytochrome P-450 (CYP) contents were diminished in SO₂-exposed rats. These results lead to two conclusions: (1) SO₂ exposure can suppress CYP2B1/2 and CYP2E1 in lungs and CYP2B1/2 in livers of rats, thus modifying the liver and lung toxication/detoxication potential, and (2) the total liver microsomal CYP contents were diminished, although the activity and mRNA expression of CYP2E1 in rat livers were not affected by SO₂ exposure.