Vascular endothelial function is improved by oral glycine treatment in aged rats

Abstract

Glycine has been used to reduce oxidative stress and proinflammatory mediators in some metabolic disorders; however, its effect on the vasculature has been poorly studied. The aim of this work was to explore the effect of glycine on endothelial dysfunction in aged rats. Aortic rings with intact or denuded endothelium were obtained from untreated or glycine-treated male Sprague-Dawley rats at 5 and 15 months of age. Concentration-response curves to phenylephrine (PHE) were obtained from aortic rings incubated with N(G)-nitro-l-arginine methyl ester (l-NAME), superoxide dismutase (SOD), indomethacin, SC-560, and NS-398. Aortic mRNA expression of endothelial nitric oxide synthase (eNOS), NADPH oxidase 4 (NOX-4), cyclooxygenase 1 (COX-1), cyclooxygenase 2 (COX-2), tumour necrosis factor (TNF)-α, and interleukin-1 β was measured by real time RT-PCR. The endothelial modulation of the contraction by PHE was decreased in aortic rings from aged rats. Glycine treatment improved this modulator effect and increased relaxation to acetylcholine. Glycine augmented the sensitivity for PHE in the presence of l-NAME and SOD. It also reduced the contraction by incubation with indomethacin, SC-560, and NS-398. Glycine increased the mRNA expression of eNOS and decreased the expression of COX-2 and TNF-α. Glycine improved the endothelium function in aged rats possibly by enhancing eNOS expression and reducing the role of superoxide anion and contractile prostanoids that increase the nitric oxide bioavailability.

Plasma Amino Acid Profile in Patients with Aortic Dissection

“…In response to diseases and malnutrition such as diabetes and starvation, plasma glycine significantly decreased2829. Gómez-Zamudio and co-workers also demonstrated that glycine could improve the endothelium function in aged rats30. In our study, glycine declined in acute AD patients, potentially indicating the possible relation between endothelium dysfunction and glycine metabolism disorder.…”

Cucumis sativus Aqueous Fraction Inhibits Angiotensin II-Induced Inflammation and Oxidative Stress In Vitro

“…These results could be due to glycine and arginine, the main compounds detected in SF1 and SF3. Both amino acids have been reported to have anti-inflammatory effects since they inhibit the expression of IL-6, IL-1β, IL-17, TNF-α, and cyclooxygenase 2, as well as macrophage infiltration; they also downregulate the activity of NF-κB [ 21 , 22 , 23 , 24 , 29 , 30 , 31 ]. However, as shown by chromatography, other compounds, related to polysaccharides, were also present in the three subtractions; these compounds could also be exerting anti-inflammatory and anti-oxidant effects as observed in other plants of the family Cucurbitaceae [ 44 , 45 ].…”

“…Glycine and arginine, the main amino acid components in both subfractions, could be responsible for this effect along with the polysaccharide content (which could not be identified). Glycine has been reported to increase the expression of eNOS mRNA and of the protein itself; thus, more enzyme is available to produce NO [ 23 , 26 ]. On the other hand, the substrate of eNOS is arginine [ 29 ]; consequently, SF1 and SF3 could act by simultaneously increasing the levels of the enzyme and its substrate to synthesize NO.…”

Evaluation of Carotid Plaque Neovascularization in Patients With Coronary Heart Disease on Contrast‐Enhanced Ultrasonography

“…The contrast enhancement intensity is an independent risk factor for the occurrence of ACS and has substantial clinical importance for the prevention and treatment of ACS. The vascular endothelial function decreases, and the permeability of endothelial cells increases with increasing age . The adhesion of inflammatory cells, movement of endothelial cells toward subendothelial tissues, and proliferation of smooth muscle cells lead to the formation of plaques …”

“…The vascular endothelial function decreases, and the permeability of endothelial cells increases with increasing age. 33 The adhesion of inflammatory cells, movement of endothelial cells toward subendothelial tissues, and proliferation of smooth muscle cells lead to the formation of plaques. 34 The repeatability of the quantitative time-intensity curve analysis software was researched in this study.…”