Resveratrol Reverses Endothelial Nitric-Oxide Synthase Uncoupling in Apolipoprotein E Knockout Mice

Abstract

A crucial cause of the decreased bioactivity of nitric oxide (NO) in cardiovascular diseases is the uncoupling of the endothelial NO synthase (eNOS) caused by the oxidative stress-mediated deficiency of the NOS cofactor tetrahydrobiopterin (BH 4 ). The reversal of eNOS uncoupling might represent a novel therapeutic approach. The treatment of apolipoprotein E knockout (ApoE-KO) mice with resveratrol resulted in the up-regulation of superoxide dismutase (SOD) isoforms (SOD1-SOD3), glutathione peroxidase 1 (GPx1), and catalase and the down-regulation of NADPH oxidases NOX2 and NOX4 in the hearts of ApoE-KO mice. This was associated with reductions in superoxide, 3-nitrotyrosine, and malondialdehyde levels. In parallel, the cardiac expression of GTP cyclohydrolase 1 (GCH1), the rate-limiting enzyme in BH 4 biosynthesis, was enhanced by resveratrol. This enhancement was accompanied by an elevation in BH 4 levels. Superoxide production from ApoE-KO mice hearts was reduced by the NOS inhibitor L-N G -nitro-arginine methyl ester, indicating eNOS uncoupling in this pathological model. Resveratrol treatment resulted in a reversal of eNOS uncoupling. Treatment of human endothelial cells with resveratrol led to an up-regulation of SOD1, SOD2, SOD3, GPx1, catalase, and GCH1. Some of these effects were preventable with sirtinol, an inhibitor of the protein deacetylase sirtuin 1. In summary, resveratrol decreased superoxide production and enhanced the inactivation of reactive oxygen species. The resulting reduction in BH 4 oxidation, together with the enhanced biosynthesis of BH 4 by GCH1, probably was responsible for the reversal of eNOS uncoupling. This novel mechanism (reversal of eNOS uncoupling) might contribute to the protective effects of resveratrol.

Recent Advances in the Study on Resveratrol

“…53,[56][57][58] At pharmacological doses, resveratrol increases vascular nitric oxide (NO) levels and improves NO bioavailability in animal models. [59][60][61][62][63][64] NO in the vasculature is constitutively synthesized by endothelial NO synthase (eNOS) and plays a crucial role in maintaining cardiovascular homeostasis. 65,66) NO relaxes vascular smooth muscle cells, thereby upregulating blood flow, and it prevents thrombogenic and atherogenic processes by vasodilatory and anti-aggregatory effects.…”

Taking up the cudgels for the traditional reactive oxygen and nitrogen species detection assays and their use in the cardiovascular system

“…Diabetic rats showed significant increase in aortic lucigenin ECL and an appreciable decrease by L-NAME, whereas lucigenin ECL was increased in aortic ring segments from control or telmisartantreated diabetic rats when incubated with L-NAME [36]. L-NAME decreased the 2-hydroxyethidium signal in HPLC measurements in heart tissue from ApoE knockout mice but increased the signal in resveratrol treated mice, which correlated well with improved BH4/ BH2 levels in resveratrol treated ApoE knockout mice [71]. Furthermore, L-NAME increased the aortic 2-hydroxyethidium content in wild-type mice, whereas L-NAME decreased this indicator of aortic superoxide formation in angiotensin-II infused mice or Nox1 overexpressing mice [72].…”

Pulmonary Hypertension Is a Probable NO/ONOO−Cycle Disease: A Review

“…Most importantly, they also showed that the synthesis of BH4 was increased by inducing increases levels of the enzyme GTP cyclohydrolase I, the rate limiting enzyme in the de novo pathway for BH4 synthesis. Not surprisingly, the increased BH4 led to increased coupling of the eNOS enzyme [308].…”

“…A study by another research group [307] showed that resveratrol increased mitochondrial biogenesis and lowered angiotensin-II-dependent activity, thus providing improvements via two distinct mechanisms. Another group [308] showed that resveratrol increases synthesis of all three superoxide dismutases (not just the mitochondrial enzyme), lowered NADPH oxidase (an important source of superoxide), lowered superoxide (not surprisingly), lowered oxidative stress, and lowered ONOO − . Most importantly, they also showed that the synthesis of BH4 was increased by inducing increases levels of the enzyme GTP cyclohydrolase I, the rate limiting enzyme in the de novo pathway for BH4 synthesis.…”