Increases in the mRNA levels of γ-Glutamyltransferase and heme oxygenase-1 in the rat lung after ozone exposure☆

Abstract γ-Glutamyltransferase (GGT) and heme oxygenase-1 (HO-1) are induced by chemical and physical stresses producing an oxidative burden on tissues and cells. Both enzymes are proposed to have an antioxidant role in protecting cells and tissues from oxidative burden. To explore the effects of ozone (O 3 ), the major oxidant in photochemical smog, on the expression of GGT and HO-1 genes in the lung, we exposed rats to 0.4 ppm O 3 for up to 7 days. After exposures, mRNA levels of GGT and HO-1 in the lung were measured by RNA blot analysis. Although a 1-day exposure did not change either GGT or HO-1 mRNA levels in the lung, both genes responded to prolonged exposure to O 3 . GGT mRNA was increased to 149% (P 3 suggests that expression of these genes is not involved in the acute respiratory response, but in the recovery process from lung damage induced by O 3 .