Elevated Mitochondrial Cytochrome P450 2E1 and Glutathione S-Transferase A4-4 in Streptozotocin-Induced Diabetic Rats

Tissue-Specific Variations and Roles in Oxidative Stress

  1. Haider Raza,
  2. Subbuswamy K. Prabu,
  3. Mari-Anne Robin and
  4. Narayan G. Avadhani
  1. Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
  1. Address correspondence and reprint requests to Narayan G. Avadhani, Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St., Philadelphia, PA 19104. E-mail: narayan{at}


Oxidative stress is an important factor in the etiology and pathogenesis of diabetes. We investigated changes in mitochondrial production of reactive oxygen species (ROS) and mitochondrial antioxidant defense systems in different tissues of streptozotocin (STZ)-induced diabetic rats. Our results show that increased ROS production and oxidative stress differentially affect mitochondrial and cytosolic glutathione (GSH) metabolism. Of the four tissues investigated, the pancreas, kidney, and brain appear to be affected more severely than the liver. We show a five- to eightfold increase of cytochrome P450 2E1 (CYP2E1) and glutathione S-transferase (GST) A4-4 levels in mitochondria from STZ-treated rat tissues compared with those in nondiabetic rat tissues, suggesting possible roles in the disease process. Transient transfection of COS cells with CYP2E1 cDNA caused a similar accumulation of CYP2E1 and GST A4-4 in mitochondria and increased production of mitochondrial ROS. Our results also show an increase in steady-state levels of Hsp70 in the mitochondrial and cytosolic fractions of different tissues of diabetic rats. These results indicate, for the first time, a marked increase in mitochondrial oxidative stress in target tissues of STZ-treated rats and implicate a direct role for mitochondrial CYP2E1 in the generation of intramitochondrial ROS.


  • H.R. is on leave from the Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates. M.-A.R. is currently located at INSERM U481, Faculté de Médecine Xavier Bichat, Paris, France.

    • Accepted October 6, 2003.
    • Received July 16, 2003.
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