Mechanisms underlying recoupling of eNOS by HMG-CoA reductase inhibition in a rat model of streptozotocin-induced diabetes mellitus.
OBJECTIVE
HMG-CoA reductase inhibitors have been shown to upregulate GTP cyclohydrolase I (GTPCH-I), the key enzyme for tetrahydrobiopterin de novo synthesis and to normalize tetrahydrobiopterin levels in hyperglycemic endothelial cells. We sought to determine whether in vivo treatment with the HMG-CoA reductase inhibitor atorvastatin is able to upregulate the GTPCH-I, to recouple eNOS and to normalize endothelial dysfunction in an experimental model of diabetes mellitus.


RESULTS
In male Wistar rats, diabetes was induced by streptozotocin (STZ, 60 mg/kg). In STZ rats, atorvastatin feeding (20 mg/kg/d, 7 weeks), normalized vascular dysfunction as analyzed by isometric tension studies, levels of circulating endothelial progenitor cells (FACS-analysis), superoxide formation (assessed by lucigenin-enhanced chemiluminescence and dihydroethidium staining), vascular levels of the phosphorylated vasodilator-stimulated phosphoprotein (P-VASP), tyrosine nitration of the prostacyclin synthase, expression of GTPCH-I, dihydrofolate reductase and eNOS, translocation of regulatory NADPH oxidase subunits rac1, p47phox and p67phox (assessed by Western blot) and vascular tetrahydrobiopterin levels as measured by HPLC. Dihydroethidine staining revealed that the reduction of vascular superoxide was at least in part due to eNOS recoupling.


CONCLUSIONS
HMG-CoA reductase inhibition normalizes endothelial function and reduces oxidative stress in diabetes by inhibiting activation of the vascular NADPH oxidase and by preventing eNOS uncoupling due to an upregulation of the key enzyme of tetrahydrobiopterin synthesis, GTPCH-I.
Second Medical Clinic, Department of Cardiology and Angiology, Johannes-Gutenberg-University, Langenbeckstrasse 1, 55131 Mainz, Germany.
Philip
P
Wenzel
Andreas
A
Daiber
Matthias
M
Oelze
Moritz
M
Brandt
Ellen
E
Closs
Jian
J
Xu
Thomas
T
Thum
Johann
J
Bauersachs
Georg
G
Ertl
Ming-Hui
MH
Zou
Ulrich
U
Förstermann
Thomas
T
Münzel
D000818:Animals; D000069059:Atorvastatin; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D001835:Body Weight; D015815:Cell Adhesion Molecules / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism; D003925:Diabetic Angiopathies / Q000188:drug therapy* / Q000378:metabolism; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D006136:GTP Cyclohydrolase / Q000378:metabolism; D006538:Heptanoic Acids / Q000494:pharmacology*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D000074624:NADPH Oxidase 1; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000187:drug effects / Q000201:enzymology; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011758:Pyrroles; D000098662:Vasodilator-Stimulated Phosphoprotein; D001708:Biopterins; D003577:Cytochrome P-450 Enzyme System; D000069059:Atorvastatin; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D013762:Tetrahydrofolate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D006136:GTP Cyclohydrolase; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase; C003402:sapropterin