Purpose We have previously shown that peroxisome proliferator-activated gamma (PPARg) ligands reduce superoxide anion (O2 2 ×) generation in vascular endothelial cells in vitro by suppressing expression of selected subunits of NADPH oxidase and by increasing the expression and activity of Cu/Zn superoxide dismutase (SOD). The current study was designed to determine if PPARg ligands modulate vascular endothelial O2 2 × generation in vivo through these same mechanisms.
Methods Lean control (db +/db 2) and obese, leptin receptor-deficient (db 2 /db 2) mice were treated with either vehicle or rosiglitazone (3 mg/kg/day) by gavage for 7 days. Aortas were prepared for analysis of O2 2 × production using ESR spectroscopy and for RNA analysis, and serum was collected for analysis of metabolic parameters.
Results Compared to db +/db 2 mice, obese, db 2 /db 2 mice had higher serum glucose, insulin, leptin, triglyceride, and fatty acid levels and lower adiponectin levels. Rosiglitazone had no effect on these metabolic derangements. Aortic O2 2 × generation measured with ESR spectroscopy was significantly increased in db 2 /db 2 mice. Aortic tissue from these mice also demonstrated higher relative mRNA levels of the NADPH oxidase subunits, Nox-1 and Nox-4, as measured by real-time PCR analysis and lower mRNA levels of PPARg. Rosiglitazone treatment decreased O2 2 × generation and mRNA levels of Nox homologues in db 2 /db 2 mice.
Conclusions These data indicate that short-term treatment with the PPARg agonist rosiglitazone suppressed vascular NADPH oxidase expression and O2 2 × production in an animal model of vascular oxidative stress. Because these findings occurred in the absence of significant metabolic effects, these results indicate that rosiglitazone and other PPARg ligands may exhibit direct vascular protective effects.
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