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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2007;27:2627.)
© 2007 American Heart Association, Inc.

Vascular Biology

Rosiglitazone Reduces Glucose-Induced Oxidative Stress Mediated by NAD(P)H Oxidase via AMPK-Dependent Mechanism

Giulio Ceolotto; Alessandra Gallo; Italia Papparella; Lorenzo Franco; Ellen Murphy; Elisabetta Iori; Elisa Pagnin; Gian Paolo Fadini; Mattia Albiero; Andrea Semplicini; Angelo Avogaro

From the Department of Clinical and Experimental Medicine (G.C., A.G., I.P., E.I., E.P., G.P.F., M.A., A.S., A.A.), Chemical Sciences (L.F.), University of Padova Medical School, Italy.

Correspondence to Prof Angelo Avogaro, Department of Clinical and Experimental Medicine, University of Padova, Via Giustiniani 2 35128 Padova, Italy. E-mail angelo.avogaro{at}unipd.it

Objective— Hyperglycemia is the main determinant of long-term diabetic complications, mainly through induction of oxidative stress. NAD(P)H oxidase is a major source of glucose-induced oxidative stress. In this study, we tested the hypothesis that rosiglitazone (RSG) is able to quench oxidative stress initiated by high glucose through prevention of NAD(P)H oxidase activation.

Methods and Results— Intracellular ROS were measured using the fluoroprobe TEMPO-9-AC in HUVECs exposed to control (5 mmol/L) and moderately high (10 mmol/L) glucose concentrations. NAD(P)H oxidase and AMPK activities were determined by Western blot. We found that 10 mmol/L glucose increased significantly ROS production in comparison with 5 mmol/L glucose, and that this effect was completely abolished by RSG. Interestingly, inhibition of AMPK, but not PPAR, prevented this effect of RSG. AMPK phosphorylation by RSG was necessary for its ability to hamper NAD(P)H oxidase activation, which was indispensable for glucose-induced oxidative stress. Downstream of AMPK activation, RSG exerts antioxidative effects by inhibiting PKC.

Conclusions— This study demonstrates that RSG activates AMPK which, in turn, prevents hyperactivity of NAD(P)H oxidase induced by high glucose, possibly through PKC inhibition. Therefore, RSG protects endothelial cells against glucose-induced oxidative stress with an AMPK-dependent and a PPAR-independent mechanism.

The present study was designed to characterize the molecular mechanisms underlying the effects of rosiglitazone on hyperglycemia-induced ROS production in HUVECs. We demonstrate that rosiglitazone reduces glucose-induced oxidative stress through inhibition of NAD(P)H oxidase. This effect is not mediated by PPAR but is dependent on AMPK activation and downstream PKC inhibition.

Key Words: diabetes • AMPK • NAD(P)H oxidase • oxidative stress • rosiglitazone