Involvement of inducible nitric oxide synthase in hydroxyl radical-mediated lipid peroxidation in streptozotocin-induced diabetes. Free Radic Biol Med 2008 Sep 15;45(6):866-74
Date
07/16/2008Pubmed ID
18620046Pubmed Central ID
PMC2613788DOI
10.1016/j.freeradbiomed.2008.06.023Scopus ID
2-s2.0-54949144344 (requires institutional sign-in at Scopus site) 78 CitationsAbstract
Free radical production is implicated in the pathogenesis of diabetes mellitus, where several pathways and different mechanisms were suggested in the pathophysiology of the complications. In this study, we used electron paramagnetic resonance (EPR) spectroscopy combined with in vivo spin-trapping techniques to investigate the sources and mechanisms of free radical formation in streptozotocin-induced diabetic rats. Free radical production was directly detected in the diabetic bile, which correlated with lipid peroxidation in the liver and kidney. EPR spectra showed the trapping of a lipid-derived radical. Such radicals were demonstrated to be induced by hydroxyl radical through isotope-labeling experiments. Multiple enzymes and metabolic pathways were examined as the potential source of the hydroxyl radicals using specific inhibitors. No xanthine oxidase, cytochrome P450s, the Fenton reaction, or macrophage activation were required for the production of radical adducts. Interestingly, inducible nitric oxide synthase (iNOS) (apparently uncoupled) was identified as the major source of radical generation. The specific iNOS inhibitor 1400W as well as L-arginine pretreatment reduced the EPR signals to baseline levels, implicating peroxynitrite as the source of hydroxyl radical production. Applying immunological techniques, we localized iNOS overexpression in the liver and kidney of diabetic animals, which was closely correlated with the lipid radical generation and 4-hydroxynonenal-adducted protein formation, indicating lipid peroxidation. In addition, protein tyrosine nitration occurred in the diabetic target organs. Taken together, our studies support inducible nitric oxide synthase as a significant source of EPR-detectable reactive intermediates, which leads to lipid peroxidation and may contribute to disease progression as well.
Author List
Stadler K, Bonini MG, Dallas S, Jiang J, Radi R, Mason RP, Kadiiska MBMESH terms used to index this publication - Major topics in bold
AnimalsBlotting, Western
Diabetes Mellitus, Experimental
Humans
Hydroxyl Radical
Immunohistochemistry
Lipid Peroxidation
Male
Microscopy, Confocal
Nitric Oxide Synthase Type II
Rats
Rats, Sprague-Dawley
Streptozocin
