title: Effects of a chronic l-arginine supplementation on the arginase pathway in aged rats.
abstract: While ageing is frequently associated with l-arginine deficiency, clinical and experimental studies provided controversial data on the interest of a chronic l-arginine supplementation with beneficial, no or even deleterious effects. It was hypothesized that these discrepancies might relate to a deviation of l-arginine metabolism towards production of l-ornithine rather than nitric oxide as a result of age-induced increase in arginase activity. This study investigated the effect of ageing on arginase activity/expression in target tissues and determined whether l-arginine supplementation modulated the effect of ageing on arginase activity. Arginase activity and expression were measured in the heart, vessel, brain, lung, kidney and liver in young rats (3-months old) and aged Wistar rats (22-24-months-old) with or without l-arginine supplementation (2.25% in drinking water for 6weeks). Plasma levels of l-arginine and l-ornithine were quantified in order to calculate the plasma l-arginine/l-ornithine ratio, considered as a reflection of arginase activity. Cardiovascular parameters (blood pressure, heart rate) and aortic vascular reactivity were also studied. Ageing dramatically reduced plasma l-arginine and l-arginine/l-ornithine ratio, decreased liver and kidney arginase activities but did not change activities in other tissues. l-Arginine supplementation normalized plasma l-arginine and l-arginine/l-ornithine ratio, improved endothelial function and decreased systolic blood pressure. These effects were associated with decreased arginase activity in aorta along with no change in the other tissues except in the lung in which activity was increased. A strong mismatch was therefore observed between arginase activity and expression in analyzed tissues. The present study reveals that ageing selectively changes arginase activity in clearance tissues, but does not support a role of the arginase pathway in the potential deleterious effect of the l-arginine supplementation in aged patients. Moreover, our data argue against the use of the measurement of plasma l-arginine/l-ornithine ratio to estimate arginase activity in aged patients.
authors.affiliation: PEPITE EA4267, FHU INCREASE, Univ. Bourgogne Franche-Comté, F-25000 Besançon, France.
authors.forename: Johnny
authors.initials: J
authors.lastname: Moretto
authors.affiliation: PEPITE EA4267, FHU INCREASE, Univ. Bourgogne Franche-Comté, F-25000 Besançon, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Guglielmetti
authors.affiliation: PEPITE EA4267, FHU INCREASE, Univ. Bourgogne Franche-Comté, F-25000 Besançon, France.
authors.forename: Maude
authors.initials: M
authors.lastname: Tournier-Nappey
authors.affiliation: PEPITE EA4267, FHU INCREASE, Univ. Bourgogne Franche-Comté, F-25000 Besançon, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Martin
authors.affiliation: INSERM U1093, Univ. Bourgogne Franche-Comté, F-21000, Dijon, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Prigent-Tessier
authors.affiliation: INSERM U1093, Univ. Bourgogne Franche-Comté, F-21000, Dijon, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Marie
authors.affiliation: PEPITE EA4267, FHU INCREASE, Univ. Bourgogne Franche-Comté, F-25000 Besançon, France. Electronic address: cdemouge@univ-fcomte.fr.
authors.forename: Céline
authors.initials: C
authors.lastname: Demougeot
mesh_terms: D000375:Aging / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001119:Arginase / Q000378:metabolism*; D001120:Arginine / Q000008:administration & dosage* / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D019587:Dietary Supplements; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D009952:Ornithine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D009952:Ornithine; D001119:Arginase
keywords: Ageing; Arginase; Rats; l-arginine supplementation