title: Effect of methionine dietary supplementation on mitochondrial oxygen radical generation and oxidative DNA damage in rat liver and heart.
abstract: Methionine restriction without energy restriction increases, like caloric restriction, maximum longevity in rodents. Previous studies have shown that methionine restriction strongly decreases mitochondrial reactive oxygen species (ROS) production and oxidative damage to mitochondrial DNA, lowers membrane unsaturation, and decreases five different markers of protein oxidation in rat heart and liver mitochondria. It is unknown whether methionine supplementation in the diet can induce opposite changes, which is also interesting because excessive dietary methionine is hepatotoxic and induces cardiovascular alterations. Because the detailed mechanisms of methionine-related hepatotoxicity and cardiovascular toxicity are poorly understood and today many Western human populations consume levels of dietary protein (and thus, methionine) 2-3.3 fold higher than the average adult requirement, in the present experiment we analyze the effect of a methionine supplemented diet on mitochondrial ROS production and oxidative damage in the rat liver and heart mitochondria. In this investigation male Wistar rats were fed either a L-methionine-supplemented (2.5 g/100 g) diet without changing any other dietary components or a control (0.86 g/100 g) diet for 7 weeks. It was found that methionine supplementation increased mitochondrial ROS generation and percent free radical leak in rat liver mitochondria but not in rat heart. In agreement with these data oxidative damage to mitochondrial DNA increased only in rat liver, but no changes were observed in five different markers of protein oxidation in both organs. The content of mitochondrial respiratory chain complexes and AIF (apoptosis inducing factor) did not change after the dietary supplementation while fatty acid unsaturation decreased. Methionine, S-AdenosylMethionine and S-AdenosylHomocysteine concentration increased in both organs in the supplemented group. These results show that methionine supplementation in the diet specifically increases mitochondrial ROS production and mitochondrial DNA oxidative damage in rat liver mitochondria offering a plausible mechanism for its hepatotoxicity.
authors.affiliation: Department of Animal Physiology II, Faculty of Biological Sciences, Complutense University, Madrid, Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Gomez
authors.forename: Pilar
authors.initials: P
authors.lastname: Caro
authors.forename: Ines
authors.initials: I
authors.lastname: Sanchez
authors.forename: Alba
authors.initials: A
authors.lastname: Naudi
authors.forename: Mariona
authors.initials: M
authors.lastname: Jove
authors.forename: Manuel
authors.initials: M
authors.lastname: Portero-Otin
authors.forename: Monica
authors.initials: M
authors.lastname: Lopez-Torres
authors.forename: Reinald
authors.initials: R
authors.lastname: Pamplona
authors.forename: Gustavo
authors.initials: G
authors.lastname: Barja
mesh_terms: D000818:Animals; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D015153:Blotting, Western; D004249:DNA Damage / Q000187:drug effects*; D019587:Dietary Supplements; D008401:Gas Chromatography-Mass Spectrometry; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000494:pharmacology*; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D051033:Apoptosis Inducing Factor; D017382:Reactive Oxygen Species; D008715:Methionine; D006861:Hydrogen Peroxide