The major objective of the present study was to determine the ability of a triazole fungicide tebuconazole to induce cytochrome P450-dependent monooxygenases, oxidative stress, and endocrine-disrupting activity using male rats treated with tebuconazole at 10, 25, and 50 mg/kg p.o. once daily for 28 days. In liver, tebuconazole dose-dependently increased microsomal contents of cytochrome P450 and cytochrome b and the activities of NADPH-cytochrome P450 reductase, 7-ethoxyresorufin O-deethylase, methoxyresorufin O-demethylase, pentoxyresorufin O-dealkylase, 7-ethoxycoumarin O-deethylase, aniline hydroxylase, and erythromycin N-demethylase. In kidney, tebuconazole increased 7-ethoxycoumarin O-deethylase activity without affecting other monooxygenase activities. In marked contrast to liver and kidney, tebuconazole decreased testicular 7-ethoxyresorufin O-deethylase, methoxyresorufin O-demethylase, 7-ethoxycoumarin O-deethylase, aniline hydroxylase, and erythromycin N-demethylase activities. The results of immunoblot analysis of liver microsomes of controls and tebuconazole-treated rats revealed that tebuconazole induced CYP1A1/2, CYP2B1/2, CYP2E1, and CYP3A proteins in liver. Additions of tebuconazole to liver microsomes inhibited microsomal 7-ethoxycoumarin O-deethylase activity in vitro (IC = 1.50-1.69 µM). Treatment of rats with tebuconazole decreased glutathione content and increased glutathione S-transferase, superoxide dismutase, catalase, and glutathione peroxidase activities in liver; increased superoxide dismutase activities in kidney and testis; but decreased glutathione S-transferase activity in testis. Treatments with tebuconazole decreased serum testosterone concentration and cauda epididymal sperm count. The present study demonstrates that tebuconazole induces a multiplicity of CYPs and oxidative stress in liver; inhibits testicular P450 and glutathione S-transferase activities; and produces anti-androgenic effects in male rats.

Motorcycle exhaust (ME) is a major source of air pollution and a potential health hazard in urban areas where motorcycles are a popular means of transportation. The main objectives of this study were to determine the ability of ME to cause cardiotoxicity in rats and investigate the possible mechanisms of toxicity. Male rats were exposed to 1:10 diluted ME by inhalation 2 h daily and Monday through Friday for 8 weeks. Exposure to ME increased heart weight and decreased cardiac antioxidant enzymes glutathione S-transferase (GST), superoxide dismutase and glutathione peroxidase activities in a concentration- and time-dependent manner. Analysis of echocardiographic parameters indicated that ME increased left ventricle posterior wall thickness, interventricular septum thickness and left ventricle mass. Histopathological examinations of the hearts revealed that ME exposure caused focal cardial degeneration and necrosis, mononuclear cell infiltration, and fibrosis. The results of reverse transcriptase-polymerase chain reaction studies showed that ME decreased GST-M1 and GST-P1 mRNA expression and increased the expression of proinflammatory cytokine interleukin-1β, hypertrophy marker atrial natriuretic peptide, fibrosis markers type I and III collagen, profibrotic cytokine connective tissue growth factor, and hypertrophy and fibrosis mediator transforming growth factor (TGF)-β1 in the heart. The data of Western blot analysis showed that cardiac TGF-β1 protein was induced by ME. These findings demonstrate that subchronic ME exposure caused hypertrophy and fibrosis, and modulated GST and TGF-β1 expression in rat heart possibly by mechanisms involving oxidative stress and inflammation.