Disruption of Nrf2 Synergizes with High Glucose to Cause Heightened Myocardial Oxidative Stress and Severe Cardiomyopathy in Diabetic MiceXiaoqing He and Qiang Ma*
Receptor Biology Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA
- *Corresponding Author:
- Qiang Ma, Mailstop 3014
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WV 26505, USA
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Received date: January 18, 2012; Accepted date: March 23, 2012; Published date: March 29, 2012
Citation: He X, Ma Q (2012) Disruption of Nrf2 Synergizes with High Glucose to Cause Heightened Myocardial Oxidative Stress and Severe Cardiomyopathy in Diabetic Mice. J Diabetes Metab S7:002. doi: 10.4172/2155-6156.S7-002
Copyright: © 2012 He X, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
High glucose-induced oxidative stress is a major contributing mechanism to the development of diabetic cardiomyopathy. Nrf2 is an emerging critical regulator of cellular defense against oxidative damage. The role of Nrf2 in diabetic cardiomyopathy was investigated in vivo. Streptozotocin (STZ) induced diabetes in Nrf2 knockout (KO) mice that rapidly progressed to severe conditions with high mortality within two weeks of injection; whereas, in wild type (WT) mice, diabetes was less severe with no death. Severe myocardial lesions were observed in diabetic KO mice that had high, sublethal levels of blood glucose including: (a) irregular myocardial arrangements, myofibrillar discontinuation, and cell death; (b) reduced electron density, discontinuation of myocardial fibers, and mitochondrial damage; and (c) markedly reduced contractility of the cardiomyocytes to β-agonist stimulation. Parallel to severe cardiomyopathy, the diabetic KO hearts showed: (a) increased apoptosis as revealed by TUNEL and PARP1 cleavage assays; (b) infiltration of granulocytes and macrophages as well as fibrosis indicating robust inflammatory response; and (c) heightened oxidative stress as evidenced by increased levels of 8-hydroxydeoxyquanine, free malondialdehyde, and 3-nitrotyrosine. Increased oxidative stress in the KO hearts was attributed to decrease or loss of the basal and induced expression of Nrf2-dependent cytoprotective genes. Our findings demonstrate that loss of Nrf2 function synergizes with high glucose to cause heightened oxidative stress in the heart leading to severe diabetic cardiomyopathy.