Resveratrol Improves Endothelial Function Role of TNFα and Vascular Oxidative Stress

Objective-Oxidative stress plays an important role in type 2 diabetes-related endothelial dysfunction. We hypothesized that resveratrol protects against oxidative stress-induced endothelial dysfunction in aortas of diabetic mice by inhibiting tumor necrosis factor alpha (TNF alpha)-induced activation of NAD(P) H oxidase and preserving phosphorylation of endothelial nitric oxide synthase (eNOS). Methods and Results-We examined endothelial-dependent vasorelaxation to acetylcholine (ACh) in diabetic mice (Lepr(db)) and normal controls (m Lepr(db)). Relaxation to ACh was blunted in Lepr(db) compared with m Lepr(db), whereas endothelial-independent vasorelaxation to sodium nitroprusside (SNP) was comparable. Resveratrol improved ACh-induced vasorelaxation in Lepr(db) without affecting dilator response to SNP. Impaired relaxation to ACh in Lepr(db) was partially reversed by incubating the vessels with NAD(P) H oxidase inhibitor apocynin and a membrane-permeable superoxide dismutase mimetic TEMPOL. Dihydroethidium (DHE) staining showed an elevated superoxide (O-2(center dot-)) production in Lepr(db), whereas both resveratrol and apocynin significantly reduced O-2(center dot-) signal. Resveratrol increased nitrite/nitrate levels and eNOS (Ser1177) phosphorylation, and attenuated H2O2 production and nitrotyrosine (N-Tyr) content in Lepr(db) aortas. Furthermore, resveratrol attenuated the mRNA and protein expression of TNF alpha. Genetic deletion of TNF alpha in diabetic mice (db(TNF-)/db(TNF-)) was associated with a reduced NAD(P) H oxidase activity and vascular O-2(center dot-) production and an increased eNOS (Ser1177) phosphorylation, suggesting that TNF alpha plays a pivotal role in aortic dysfunction in diabetes by inducing oxidative stress and reducing NO bioavailability. Conclusions-Resveratrol restored endothelial function in type 2 diabetes by inhibiting TNF alpha-induced activation of NAD(P) H oxidase and preserving eNOS phosphorylation, suggesting the potential for new treatment approaches to promote vascular health in metabolic diseases. (Arterioscler Thromb Vasc Biol. 2009; 29: 1164-1171.)