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

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Publisher: NRC Research Press
Document Type: Report
Length: 5,547 words
Lexile Measure: 1370L

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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 NG-nitro-L-arginme methyl ester (L-NAME), superoxide dismutase (SOD), indo methacin, 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)-[alpha], and interleukin-1 p 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-[alpha]. 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. Key words: aging, endothelium dysfunction, glycine, aortic contraction. La glycine a ete utilisee afin de reduire le stress oxydant et les mediateurs pro-inflammatoires dans certains troubles metaboliques; cependant, son effet sur la vasculature a ete peu etudie. Le but de cette etude etait d'explorer l'effet de la glycine sur la dysfonction endotheliale chez les rats ages. Des anneaux aortiques dont l'endothelium etait intact ou denude ont ete preleves de rats males Sprague-Dawley traites ou non a la glycine, a 5 et 15 mois d'age. Les courbes de reponses en fonction de la concentration a la phenylephrine (PHE) ont ete obtenues d'anneaux aortiques incubes en presence de [N.sup.G]-nitro-L-arginine methyl ester (L-NAME), de la superoxyde dismutase (SOD), indometacine, SC-560 et NS-398. L'expression de l'ARNm de la synthase d'oxyde nitrique endotheliale (eNOS), de NADPH oxydase-1 (NOX-4), de la cyclooxygenase-1 (COX-1), de la cyclooxygenase-2 (COX-2), du facteur necrosant des tumeurs (TNF)-[alpha] et l'interleukine-1 [beta] dans l'aorte a ete mesuree par RT-PCR en temps reel. La modulation endotheliale de la contraction par la PHE etait diminuee dans les anneaux aortiques des rats ages. Le traitement a la glycine ameliorait l'effet de ce modulateur et accroissait la relaxation en reponse a l'acetylcholine. La glycine accroissait la sensibilite a la PHE en presence de L-NAME et de SOD. Elle reduisait aussi la contraction a la suite de l'incubation en presence d'indometacine, de SC-560 et de NS-398. La glycine accroissait l'expression de l'ARNm de eNOS et diminuait l'expression de COX-2 et de TNF-[alpha]. La glycine ameliorait la fonction endotheliale chez les rats ages possiblement en augmentant l'expression de eNOS et en reduisant le role de l'anion superoxyde et des prostanoides contractiles qui accroissent la biodisponibilite d'oxyde nitrique. [Traduit par la Redaction] Mots-cles: vieillissement, dysfonction endotheliale, glycine, contraction aortique.

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Gale Document Number: GALE|A418467733