Enriching Eggs with Bioactive Compounds through the Inclusion of Grape Pomace in Laying Hens Diet: Effect on Internal and External Egg Quality Parameters.

(1) Background: Grapes and their associated by-products (such as grape pomace, GP) stand out for their polyphenol content, which makes them a source of bioactive compounds with antioxidant capacity. The aim of this research was to determine if the inclusion of 50 g/kg of GP in the diet of hens could enrich eggs with antioxidants and to study its effect on internal and external egg quality parameters. (2) Methods: A trial was conducted with two genetic lines of hens, which were fed either a control diet or a diet containing 50 g/kg of GP. Performance, internal and external egg quality, and egg yolk content of vitamins E and A and gallic acid were determined. (3) Results: In eggs laid by hens fed a GP diet, Haugh units and yolk color scores were enhanced, and eggshells became thinner, but without affecting the breaking strength. No dietary effect was observed on the vitamin contents of the yolk. A higher gallic acid content was observed in the yolks of eggs laid by hens fed the GP diet, suggesting that some dietary phenolic compounds could be transferred to the eggs. Hen genetics influenced egg weight, albumen Haugh units, shell thickness, and α- and γ-tocopherol concentration in yolks. (4) Conclusions: Dietary inclusion of GP improved the internal quality of eggs, enriching yolks with a phenolic compound but reducing shell thickness.

Mitochondrial base excision repair positively correlates with longevity in the liver and heart of mammals.

Damage to DNA is especially important for aging. High DNA repair could contribute, in principle, to lower such damage in long-lived species. However, previous studies showed that repair of endogenous damage to nuclear DNA (base excision repair, BER) is negatively or not correlated with mammalian longevity. However, we hypothesize here that mitochondrial, instead of nuclear, BER is higher in long-lived than in short-lived mammals. We have thus measured activities and/or protein levels of various BER enzymes including DNA glycosylases, NTHL1 and NEIL2, and the APE endonuclease both in total and mitochondrial liver and heart fractions from up to eight mammalian species differing by 13-fold in longevity. Our results show, for the first time, a positive correlation between (mitochondrial) BER and mammalian longevity. This suggests that the low steady-state oxidative damage in mitochondrial DNA of long-lived species would be due to both their lower mitochondrial ROS generation and their higher mitochondrial BER. Long-lived mammals do not need to continuously maintain high nuclear BER levels because they release less mitROS to the cytosol. This can be the reason why they tend to show lower nuclear BER values. The higher mitochondrial BER of long-lived mammals contributes to their superior longevity, agrees with the updated version of the mitochondrial free radical theory of aging, and indicates the special relevance of mitochondria and mitROS for aging.

Lifelong treatment with atenolol decreases membrane fatty acid unsaturation and oxidative stress in heart and skeletal muscle mitochondria and improves immunity and behavior, without changing mice longevity.

The membrane fatty acid unsaturation hypothesis of aging and longevity is experimentally tested for the first time in mammals. Lifelong treatment of mice with the ß1-blocker atenolol increased the amount of the extracellular-signal-regulated kinase signaling protein and successfully decreased one of the two traits appropriately correlating with animal longevity, the membrane fatty acid unsaturation degree of cardiac and skeletal muscle mitochondria, changing their lipid profile toward that present in much more longer-lived mammals. This was mainly due to decreases in 22:6n-3 and increases in 18:1n-9 fatty acids. The atenolol treatment also lowered visceral adiposity (by 24%), decreased mitochondrial protein oxidative, glycoxidative, and lipoxidative damage in both organs, and lowered oxidative damage in heart mitochondrial DNA. Atenolol also improved various immune (chemotaxis and natural killer activities) and behavioral functions (equilibrium, motor coordination, and muscular vigor). It also totally or partially prevented the aging-related detrimental changes observed in mitochondrial membrane unsaturation, protein oxidative modifications, and immune and behavioral functions, without changing longevity. The controls reached 3.93 years of age, a substantially higher maximum longevity than the best previously described for this strain (3.0 years). Side effects of the drug could have masked a likely lowering of the endogenous aging rate induced by the decrease in membrane fatty acid unsaturation. We conclude that it is atenolol that failed to increase longevity, and likely not the decrease in membrane unsaturation induced by the drug.

Independent and additive effects of atenolol and methionine restriction on lowering rat heart mitochondria oxidative stress.

A low rate of mitochondrial ROS production (mitROSp) and a low degree of fatty acid unsaturation are characteristic traits of long-lived animals and can be obtained in a single species by methionine restriction (MetR) or atenolol (AT) treatments. However, simultaneous application of both treatments has never been performed. In the present investigation it is shown that MetR lowers mitROSp and complex I content. Both the MetR and the AT treatments lower protein oxidative modification and oxidative damage to mtDNA and the fatty acid unsaturation degree in rat heart mitochondria. The decrease in fatty acid unsaturation seems to be due, at least in part, to decreases in desaturase and elongase activities or peroxisomal ß-oxidation. Furthermore, the phosphorylation of extracellular signal-regulated kinase (ERK) was stimulated by MetR and AT. The decrease in membrane fatty acid unsaturation and protein oxidation, and the changes in fatty acids and p-ERK showed additive effects of both treatments. In addition, the increase in mitROSp induced by AT observed in the present investigation was totally avoided with the combined MetR + AT treatment. It is concluded that the simultaneous treatment with MetR plus atenolol is more beneficial than either single treatment alone to lower oxidative stress in rat heart mitochondria, analogously to what has been reported in long-lived animal species.

Reducción en el índice de peroxidizabilidad de la membrana mitocondrial y niveles de lipoxidación proteícos en el corazón de la rata después de la interrupción de la señalización del receptor betaadrenérgico con el betabloqueante atenolol / Reduction in mitochondrial membrane peroxidizability index and protein lipoxidation levels in the rat heart after ß-adrenergic receptor signaling interruption with the ß-blocker atenolol

Un nuevo modelo de longevidad en mamíferos basado en la interrupción de la vía de señalización beta-adrenérgica a nivel de la adenilato ciclasa ha revelado una ralentización del envejecimiento del corazón y el hueso de ratones AC5KO y un incremento de su longevidad media y máxima [1]. Decidimos mimetizar este modelo en ratas Wistar utilizando atenolol en el agua de bebida para comprobar si un descenso de estrés oxidativo podría estar implicado. El tratamiento no modificó la tasa de generación de radicales y el daño oxidativo al ADN del corazón, pero si redujo el índice de peroxidizabilidad y la lipoxidación proteica de las membranas mitocondriales, probablemente debido a cambios en las actividades elongasas y desaturasas (AU)

A new mammalian longevity model based on ß-adrenergic signaling interruption at the level of adenylyl cyclase has reported decreased bone and heart aging and mean and maximum longevity increases in AC5KO mice (1). We decided to mimic this model in male Wistar rats treated with the ß-blocker atenolol in the drinking water and to check if an oxidative stress decrease could be involved. Atenolol treatment did not modify heart mitROS generation rate and mitDNA oxidative damage but significantly decreased global peroxidizability index of mitochondrial membranes, as well as protein lipoxidation, probably mediated by changes in elongases and desaturases activities (AU)

Significado de las experiencias del profesional de enfermería ante el proceso de la muerte de un paciente en la unidad de cuidado intensivo adulto / Meaning of the experiences of the nursing professional in the process of the death of a patient in the adult intensive care unit

La muerte es la última etapa del proceso de la vida del ser humano. Los profesionales de Enfermería que trabajan en las unidades de cuidado intensivo, tienen que enfrentarse a este proceso a diario, pues las personas que ingresan allí tienen alto riesgo de morir por su condición de enfermedad. Conocer el significado que tienen los profesionales de enfermería de sus experiencias ante la muerte de un paciente, da a Enfermería y a la disciplina, conocimientos sobre las prácticas de cuidado humanizado ante la otra razón del ser de la profesión: el cuidado ante la muerte. Como objetivo se planteó descubrir el significado de las experiencias del profesional de enfermería ante el proceso de muerte de un paciente en la Unidad de Cuidado Intensivo Adulto. Esta investigación es cualitativa, tipo descriptivo interpretativo, se utilizó la entrevista a profundidad, la cual fue trascrita en su totalidad, utilizando la pregunta: ¿Quiere compartir conmigo como ha sido la experiencia cuando se ve enfrentado a la muerte de un paciente en la unidad?. Los participantes fueron seis profesionales de enfermería, con un promedio de tres entrevistas por cada uno. Se utilizaron las notas de campo como registro de observaciones, impresiones e interpretaciones de la entrevista. Los resultados de ésta investigación fueron: como tema principal "el contacto con la muerte enseña a verla de manera diferente" y cuatro categorías: la edad marca la diferencia, estar ahí en la partida, reflexión sobre lo sucedido y lo que no quiero llegar a ser. Se concluye que las condiciones del paciente son el punto de partida para brindar un cuidado humanizado e integral, el cual hace que surja en el profesional el deseo de despedirse y reflexionar sobre la muerte y cómo le afecta. (AU)

Death is a natural process that puts an end to human life. Nursing professionals working in intensive care units, have to face this process day after day, thus people who enter there have a high risk of dying from their disease condition. Knowing the meanings nurses have of their experiences at the death of a patient, gives nursing and the discipline knowledge of humanized care practices to the other raison d'etre of the profession: care before death. As an objective to discover the meaning of the experiences of the nurse to the dying process of a patient in the Intensive Adult Care Unit is proposed. This research is qualitative, descriptive, and interpretive. We used the depth interview, which was transcribed in full, using the question Do you want to share with me how the experience when confronted with the death of a patient in the unit has been? The participants were six nurses, with an average of three interviews each. We used the field notes as a means of recording observations, impressions and interpretations of the interview. As a result of this investigation the results were: as a main topic "contact with death teach by itself to appreciate it in a different way" and four categories: age makes a difference, being there in the game, thinking about what happened and what I do not want to become. It is concluded that the patient's conditions are the starting point to provide a comprehensive and humane care, which raises the desire in the professional to farewell and reflect about death and how it affects oneself. (AU)

Effects of aging and methionine restriction applied at old age on ROS generation and oxidative damage in rat liver mitochondria.

It is known that a global decrease in food ingestion (dietary restriction, DR) lowers mitochondrial ROS generation (mitROS) and oxidative stress in young immature rats. This seems to be caused by the decreased methionine ingestion of DR animals. This is interesting since isocaloric methionine restriction in the diet (MetR) also increases, like DR, rodent maximum longevity. However, it is not known if old rats maintain the capacity to lower mitROS generation and oxidative stress in response to MetR similarly to young immature animals, and whether MetR implemented at old age can reverse aging-related variations in oxidative stress. In this investigation the effects of aging and 7 weeks of MetR were investigated in liver mitochondria of Wistar rats. MetR implemented at old age decreased mitROS generation, percent free radical leak at the respiratory chain and mtDNA oxidative damage without changing oxygen consumption. Protein oxidation, lipoxidation and glycoxidation increased with age, and MetR in old rats partially or totally reversed these age-related increases. Aging increased the amount of SIRT1, and MetR decreased SIRT1 and TFAM and increased complex IV. No changes were observed in the protein amounts of PGC1, Nrf2, MnSOD, AIF, complexes I, II and III, and in the extent of genomic DNA methylation. In conclusion, treating old rats with isocaloric short-term MetR lowers mitROS production and free radical leak and oxidative damage to mtDNA, and reverses aging-related increases in protein modification. Aged rats maintain the capacity to lower mitochondrial ROS generation and oxidative stress in response to a short-term exposure to restriction of a single dietary substance: methionine.

Forty percent methionine restriction lowers DNA methylation, complex I ROS generation, and oxidative damage to mtDNA and mitochondrial proteins in rat heart.

Methionine dietary restriction (MetR), like dietary restriction (DR), increases rodent maximum longevity. However, the mechanism responsible for the retardation of aging with MetR is still not entirely known. As DR decreases oxidative damage and mitochondrial free radical production, it is plausible to hypothesize that a decrease in oxidative stress is the mechanism for longevity extension with MetR. In the present investigation male Wistar rats were subjected to isocaloric 40% MetR during 7 weeks. It was found that 40% MetR decreases heart mitochondrial ROS production at complex I during forward electron flow, lowers oxidative damage to mitochondrial DNA and proteins, and decreases the degree of methylation of genomic DNA. No significant changes occurred for mitochondrial oxygen consumption, the amounts of the four respiratory complexes (I to IV), and the mitochondrial protein apoptosis-inducing factor (AIF). These results indicate that methionine can be the dietary factor responsible for the decrease in mitochondrial ROS generation and oxidative stress, and likely for part of the increase in longevity, that takes place during DR. They also highlight some of the mechanisms involved in the generation of these beneficial effects.

Methionine and homocysteine modulate the rate of ROS generation of isolated mitochondria in vitro.

Dietary methionine restriction and supplementation in mammals have beneficial (antiaging) and detrimental effects respectively, which have been related to chronic modifications in the rate of mitochondrial ROS generation. However it is not known if methionine or its metabolites can have, in addition, direct effects on the rate of mitochondrial ROS production. This is studied here for the methionine cycle metabolites S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine and methionine itself in isolated rat liver, kidney, heart, and brain mitochondria. The results show that methionine increases ROS production in liver and kidney mitochondria, homocysteine increases it in kidney and decreases it in the other three organs, and SAM and SAH have no effects. The variations in ROS production are localized at complexes I or III. These changes add to previously described chronic effects of methionine restriction and supplementation in vivo.

The ß-blocker atenolol lowers the longevity-related degree of fatty acid unsaturation, decreases protein oxidative damage, and increases extracellular signal-regulated kinase signaling in the heart of C57BL/6 mice.

The interruption of the ß-adrenergic receptor signaling at the level of adenylyl cyclase (AC) by specifically knocking out (KO) the AC5 gene activates the RAF/MEK/ extracellular signal-regulated kinase (ERK) signaling pathway, delays bone and heart aging, and increases mean and maximum longevity in mice. However, the mechanisms involved in life extension in this animal model with increased longevity have not been clarified, although a decrease in oxidative stress has been proposed as mediator. Two traits link longevity and oxidative stress. Long-lived mammals and birds have a low rate of mitochondrial reactive oxygen species (mitROS) generation and a low degree of membrane fatty acid unsaturation, but these key factors have not been studied in AC5 KO mice. In the present investigation, male C57BL/6 mice were treated with the ß-blocker atenolol in drinking water, and oxidative stress-related parameters were measured in the heart. Atenolol treatment did not change the rate of mitROS production and oxidative damage to mitDNA (8-oxo-7,8-dihydro-2'-deoxyguanosine [8-oxodG]), but strongly decreased the degree of fatty acid unsaturation and the peroxidizability index, mainly due to decreases in 22:6n-3 and 20:4n-6 and to increases in 18:1n-9, 16:1n-7 and 16:0 in the atenolol group. Protein oxidation and lipoxidation were lower in the atenolol group than in the controls. The mitochondrial complex I and IV content and the amount of p-ERK1/2 signaling proteins were significantly higher in the atenolol-treated than in the control animals. These results support the idea that the increased longevity of the AC5 KO mice can be due in part to an ERK signaling-mediated stress-resistance due to a decrease in fatty acid unsaturation, leading to lower lipid peroxidation and decreased lipoxidation-derived damage to cellular proteins.

Efecto de la restricción de aminoácidos excepto la metionina sobre el estrés oxidativo mitocondrial / Effect of restricting amino acids except methionine on mitochondrial oxidative stress

Introducción Se sabe que la restricción de proteína o la restricción de metionina (RMet) en la dieta disminuye la producción de radicales de oxígeno (ROS) y el estrés oxidativo mitocondrial y aumenta la longevidad máxima en roedores, lo que puede explicar que estos cambios ocurran en la restricción calórica. Sin embargo, no se sabe si la restricción de otros aminoácidos está también implicada. Para aclararlo, se estudió el efecto de la restricción al 40% de todos los aminoácidos de la dieta semipurificada AIN 93G, excepto la metionina, en ratas Wistar.Material y métodos Dieciséis ratas Wistar macho de 7 semanas de edad se dividieron aleatoriamente en 2 grupos: el grupo control y el grupo restringido al 40% en los aminoácidos de la dieta, excepto la metionina. Tras 7 semanas de régimen dietético los animales se sacrificaron y se les extrajo el hígado para aislar inmediatamente las mitocondrias y medir la producción de ROS y el consumo de oxígeno en éstas. Con estos datos se calculó la fuga porcentual de radicales libres. El daño oxidativo al ADN mitocondrial se estimó como 8-oxo-7,8-dihidro-2′-deoxiguanosina por cromatografía líquida de alta resolución con detección electroquímica (HPLC-EC).Resultados Al final del período experimental se observó un descenso del peso del riñón, pero no del hígado, ni del corazón o del cerebro. La producción de ROS en mitocondrias hepáticas aisladas no se modificó ni con sustratos del complejo I (piruvato con malato o glutamato con malato) ni del complejo II (succinato). La producción máxima de ROS disminuyó significativamente con glutamato, malato y rotenona pero no con piruvato, malato y rotenona ni con succinato. No hubo cambios en el consumo de oxígeno con ningún sustrato ni en estado 4 (reposo) ni en estado 3 (fosforilante). De acuerdo con los resultados de producción de ROS, no hubo diferencias entre los grupos en el daño oxidativo al ADNm(AU)

Introduction Protein or methionine restriction in the diet is known to decrease reactive oxygen species (ROS) production and mitochondrial oxidative stress and to increase maximum longevity in rodents, which could explain how these changes also take place in dietary restriction. However, it is not known whether restriction of other amino acids is also involved. To clarify this question, we studied the effect of restricting all the amino acids, except methionine, of the semi-purified diet, AIN 93G, in Wistar rats. Material and methods Seven-week old male Wistar rats (n=16) were randomly divided into two groups: a control group and a group with 40% restriction of dietary amino acids except methionine. After 7 weeks of dietary treatment, the animals were sacrificed and their livers were extracted to isolate mitochondria immediately and measure ROS production and oxygen consumption; these data allowed the percentage of free radical leak to be calculated. Oxidative damage to mitochondrial DNA was calculated as 8-oxo-7,8-dihydro-2′-deoxyguanosine by HPLC-EC. Results At the end of the experimental period decrease in kidney weight was observed, but the weight of the liver, heart and brain was unchanged. ROS production in isolated liver mitochondria was unchanged with complex I (pyruvate/malate or glutamate/malate) or complex II (succinate) linked substrates. Maximum rates of ROS production significantly decreased with glutamate/malate+rotenone but not with pyruvate/malate+rotenone or with succinate. There were no changes in oxygen consumption with any substrate either in state 4 (resting) or in state 3 (phosphorylating). In agreement with the ROS production results, there were no differences between groups in oxidative damage to mitochondrial DNA.Conclusions Taken together with previous results concerning methionine restriction, the results obtained in the (..) (AU)

Effect of methionine dietary supplementation on mitochondrial oxygen radical generation and oxidative DNA damage in rat liver and heart.

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.

[Effect of restricting amino acids except methionine on mitochondrial oxidative stress]. / Efecto de la restricción de aminoácidos excepto la metionina sobre el estrés oxidativo mitocondrial.

INTRODUCTION: Protein or methionine restriction in the diet is known to decrease reactive oxygen species (ROS) production and mitochondrial oxidative stress and to increase maximum longevity in rodents, which could explain how these changes also take place in dietary restriction. However, it is not known whether restriction of other amino acids is also involved. To clarify this question, we studied the effect of restricting all the amino acids, except methionine, of the semi-purified diet, AIN 93G, in Wistar rats. MATERIAL AND METHODS: Seven-week old male Wistar rats (n=16) were randomly divided into two groups: a control group and a group with 40% restriction of dietary amino acids except methionine. After 7 weeks of dietary treatment, the animals were sacrificed and their livers were extracted to isolate mitochondria immediately and measure ROS production and oxygen consumption; these data allowed the percentage of free radical leak to be calculated. Oxidative damage to mitochondrial DNA was calculated as 8-oxo-7,8-dihydro-2'-deoxyguanosine by HPLC-EC. RESULTS: At the end of the experimental period, a decrease in kidney weight was observed, but the weight of the liver, heart and brain was unchanged. ROS production in isolated liver mitochondria was unchanged with complex I (pyruvate/malate or glutamate/malate) or complex II (succinate) linked substrates. Maximum rates of ROS production significantly decreased with glutamate/malate+rotenone but not with pyruvate/malate+rotenone or with succinate. There were no changes in oxygen consumption with any substrate either in state 4 (resting) or in state 3 (phosphorylating). In agreement with the ROS production results, there were no differences between groups in oxidative damage to mitochondrial DNA. CONCLUSIONS: Taken together with previous results concerning methionine restriction, the results obtained in the present study clearly show that the decrease in ingestion of only one molecule, methionine, causes the decrease in ROS production and oxidative damage to mitochondrial DNA that is observed in dietary restriction in relation to the decrease in the rate of aging.

Effect of 40% restriction of dietary amino acids (except methionine) on mitochondrial oxidative stress and biogenesis, AIF and SIRT1 in rat liver.

Previous studies have shown that the decrease in mitochondrial reactive oxygen species (mitROS) generation and oxidative damage to mitochondrial DNA (mtDNA) that occurs during life extending dietary restriction also occurs during protein or methionine restriction, whereas it does not take place during carbohydrate or lipid restriction. In order to study the possible effects of other amino acids, in this investigation all the dietary amino acids, except methionine, were restricted by 40% in male Wistar rats (RESTAAS group). After 6-7 weeks, experimental parameters were measured in the liver. Amino acid restriction did not change the levels of the methionine metabolites S-adenosylmethionine and S-adenosylhomocysteine, mitochondrial oxygen consumption and ROS generation, oxidative damage to mtDNA, amounts of the respiratory complexes I-IV, and the mitochondrial biogenesis factors PGC-1alpha and NRF-2. On the other hand, adenylate energy charge, mitochondrial protein oxidation, lipooxidation and glycooxidation, the degree of mitochondrial fatty acid unsaturation, and the amount of the apoptosis inducing factor (AIF) were decreased in the RESTAAS group. Amino acid restriction also increased SIRT1 protein. These results, together with previous ones, strongly suggest that the decrease in mitROS generation and oxidative damage to mtDNA that occurs during dietary restriction is due to restriction of a single aminoacid: methionine. They also show for the first time that restriction of dietary amino acids different from methionine decreases mitochondrial protein oxidative modification and AIF, and increases SIRT1, in rat liver.

Forty percent methionine restriction decreases mitochondrial oxygen radical production and leak at complex I during forward electron flow and lowers oxidative damage to proteins and mitochondrial DNA in rat kidney and brain mitochondria.

Eighty percent dietary methionine restriction (MetR) in rodents (without calorie restriction), like dietary restriction (DR), increases maximum longevity and strongly decreases mitochondrial reactive oxygen species (ROS) production and oxidative stress. Eighty percent MetR also lowers the degree of membrane fatty acid unsaturation in rat liver. Mitochondrial ROS generation and the degree of fatty acid unsaturation are the only two known factors linking oxidative stress with longevity in vertebrates. However, it is unknown whether 40% MetR, the relevant methionine restriction degree to clarify the mechanisms of action of standard (40%) DR can reproduce these effects in mitochondria from vital tissues of strong relevance for aging. Here we study the effect of 40% MetR on ROS production and oxidative stress in rat brain and kidney mitochondria. Male Wistar rats were fed during 7 weeks semipurified diets differing only in their methionine content: control or 40% MetR diets. It was found that 40% MetR decreases mitochondrial ROS production and percent free radical leak (by 62-71%) at complex I during forward (but not during reverse) electron flow in both brain and kidney mitochondria, increases the oxidative phosphorylation capacity of brain mitochondria, lowers oxidative damage to kidney mitochondrial DNA, and decreases specific markers of mitochondrial protein oxidation, lipoxidation, and glycoxidation in both tissues. Forty percent MetR also decreased the amount of respiratory complexes I, III, and IV and apoptosis-inducing factor (AIF) in brain mitochondria and complex IV in kidney mitochondria, without changing the degree of mitochondrial membrane fatty acid unsaturation. Forty percent MetR, differing from 80% MetR, did not inhibit the increase in rat body weight. These changes are very similar to the ones previously found during dietary and protein restriction in rats. We conclude that methionine is the only dietary factor responsible for the decrease in mitochondrial ROS production and oxidative stress, and likely for part of the longevity extension effect, occurring in DR.

[Calorie restriction, oxidative stress and longevity]. / Restricción calórica, estrés oxidativo y longevidad.

Studies on the relationship between oxidative stress and ageing in different vertebrate species and in calorie-restricted animals are reviewed. Endogenous antioxidants inversely correlate with maximum longevity in animal species and experiments modifying levels of these antioxidants can increase survival and mean life span but not maximum life span (MLSP). The available evidence shows that long-living vertebrates consistently have low rates of mitochondrial free radical generation, as well as a low grade of fatty acid unsaturation on cellular membranes, which are two crucial factors determining their ageing rate. Oxidative damage to mitochondrial DNA is also lower in long-living vertebrates than in short-living vertebrates. Calorie restriction, the best described experimental strategy that consistently increases mean and maximum life span, also decreases mitochondrial reactive oxygen species (ROS) generation and oxidative damage to mitochondrial DNA. Recent data indicate that the decrease in mitochondrial ROS generation is due to protein restriction rather than to calorie restriction, and more specifically to dietary methionine restriction. Greater longevity would be partly achieved by a low rate of endogenous oxidative damage generation, but also by a macromolecular composition highly resistant to oxidative modification, as is the case for lipids and proteins.

Effect of every other day feeding on mitochondrial free radical production and oxidative stress in mouse liver.

It is known that dietary restriction (DR) increases maximum longevity in rodents, but the mechanisms involved remain unknown. Among the possible mechanisms, several lines of evidence support the idea that decreases in mitochondrial oxidative stress and in insulin signaling are involved but it is not known if they are interconnected. It has been reported that when C57BL/6 mice are maintained on an every other day (EOD) feeding their overall food intake is only slightly decreased and plasma insulin-like growth factor (IGF)-1 is even somewhat increased. In spite of this, their maximum longevity is increased, analogously to what occurs in classic DR. Thus, this model dissociates the increase in longevity from the decrease in IGF-1 observed in classic DR. Based on these facts, we have studied the effect of EOD DR on the rate of mitochondrial reactive oxygen species (ROS) production, oxygen consumption, and the percent free radical leak (FRL) of well-coupled liver mitochondria, the marker of mtDNA oxidative damage 8-oxo-7,8-dihydro-2'deoxyguanosine (8-oxodG), the content of complexes I to IV of the respiratory chain, the apoptosis inducing factor (AIF), PGC1-alpha, UCP2, five different markers of oxidative damage to proteins and the full fatty acid composition on C57BL/6 mice liver. It was found that EOD DR decreased ROS production in complex I but not in complex III without changes in oxygen consumption. As a result, FRL was decreased in complex I. Oxidative damage to mtDNA (8-oxodG) and protein oxidation, glycoxidation and lipoxidation were also lower in the EOD restricted group in comparison with the control one while the degree of fatty acid unsaturation was held constant. The EOD group also showed decreases in AIF, PGC1-alpha, and UCP2. These results support the possibility that EOD DR increases maximum life span at least in part through decreases in mitochondrial oxidative stress which are independent from insulin/IGF-1-like signaling.

Restricción calórica, estrés oxidativo y longevidad / Calorie restriction, oxidative stress and longevity

En el presente artículo se revisan los estudios disponibles acerca de la relación entre el estrés oxidativo y el envejecimiento en distintasespecies de vertebrados y en mamíferos sometidos a restricción calórica (RC). Los antioxidantes endógenos correlacionan de modo inverso con la longevidad máxima de las especies animales y los experimentos que modifican sus valores pueden aumentar la supervivencia y la longevidad media pero no la longevidad máxima. Los datos disponibles indican que las especies longevas de vertebrados tienen tasas bajas de producción mitocondrial de radicales libres y un grado bajo de instauración de los ácidos grasos de sus membranas, dos factores cruciales que pueden determinar su lenta velocidad de envejecimiento. El daño oxidativo al ADN mitocondrial es también menor en las especies de vertebrados longevos que en las de vida corta. Por otra parte, la RC, la manipulación experimental mejor descrita que aumenta las longevidades media y máxima, también disminuye la producción mitocondrial de especies reactivas derivadas del oxígeno (ROS) y el daño oxidativo al ADN mitocondrial. Datos recientesindican que el descenso en generación mitocondrial de ROS se debe a la restricción proteica en vez de a la de calorías, y más concretamente a la restricción de metionina en la dieta. Una mayor longevidad se conseguiría en parte mediante una baja tasa de generación de daño oxidativo endógeno y también mediantela posesión de macromoléculas altamente resistentes a la modificación oxidativa, como es el caso de las proteínas y los lípidos titulares

Studies on the relationship between oxidative stress and ageing in different vertebrate species and in calorie-restricted animals are reviewed. Endogenous antioxidants inversely correlate with maximum longevity in animal species and experiments modifying levels of these antioxidants can increase survival and mean lifespan but not maximum life span (MLSP). The available evidence shows that long-living vertebrates consistently have low rates of mitochondrial free radical generation, as well as a low grade of fatty acid unsaturation on cellular membranes, which are two crucial factors determining their ageing rate. Oxidative damage to mitochondrial DNA is also lower in long-living vertebrates than in short-living vertebrates. Calorie restriction, the best described experimental strategy that consistently increases mean and maximumlife span, also decreases mitochondrial reactive oxygenspecies (ROS) generation and oxidative damage to mitochondrial DNA. Recent data indicate that the decrease in mitochondrial ROS generation is due to protein restriction rather than to calorierestriction, and more specifically to dietary methionine restriction. Greater longevity would be partly achieved by a low rate of endogenous oxidative damage generation, but also by a macromolecular composition highly resistant to oxidative modification, as isthe case for lipids and proteins

Lowered methionine ingestion as responsible for the decrease in rodent mitochondrial oxidative stress in protein and dietary restriction possible implications for humans.

Available information indicates that long-lived mammals have low rates of reactive oxygen species (ROS) generation and oxidative damage at their mitochondria. On the other hand, many studies have consistently shown that dietary restriction (DR) in rodents also decreases mitochondrial ROS (mtROS) production and oxidative damage to mitochondrial DNA and proteins. It has been observed that protein restriction also decreases mtROS generation and oxidative stress in rat liver, whereas neither carbohydrate nor lipid restriction change these parameters. This is interesting because protein restriction also increases maximum longevity in rodents (although to a lower extent than DR) and is a much more practicable intervention for humans than DR, whereas neither carbohydrate nor lipid restriction seem to change rodent longevity. Moreover, it has been found that isocaloric methionine restriction also decreases mtROS generation and oxidative stress in rodent tissues, and this manipulation also increases maximum longevity in rats and mice. In addition, excessive dietary methionine also increases mtROS generation in rat liver. These studies suggest that the reduced intake of dietary methionine can be responsible for the decrease in mitochondrial ROS generation and the ensuing oxidative damage that occurs during DR, as well as for part of the increase in maximum longevity induced by this dietary manipulation. In addition, the mean intake of proteins (and thus methionine) of Western human populations is much higher than needed. Therefore, decreasing such levels to the recommended ones has a great potential to lower tissue oxidative stress and to increase healthy life span in humans while avoiding the possible undesirable effects of DR diets.

Forty percent and eighty percent methionine restriction decrease mitochondrial ROS generation and oxidative stress in rat liver.

Dietary restriction (DR) lowers mitochondrial reactive oxygen species (ROS) generation and oxidative damage and increases maximum longevity in rodents. Protein restriction (PR) or methionine restriction (MetR), but not lipid or carbohydrate restriction, also cause those kinds of changes. However, previous experiments of MetR were performed only at 80% MetR, and substituting dietary methionine with glutamate in the diet. In order to clarify if MetR can be responsible for the lowered ROS production and oxidative stress induced by standard (40%) DR, Wistar rats were subjected to 40% or 80% MetR without changing other dietary components. It was found that both 40% and 80% MetR decrease mitochondrial ROS generation and percent free radical leak in rat liver mitochondria, similarly to what has been previously observed in 40% PR and 40% DR. The concentration of complexes I and III, apoptosis inducing factor, oxidative damage to mitochondrial DNA, five different markers of protein oxidation, glycoxidation or lipoxidation and fatty acid unsaturation were also lowered. The results show that 40% isocaloric MetR is enough to decrease ROS production and oxidative stress in rat liver. This suggests that the lowered intake of methionine is responsible for the decrease in oxidative stress observed in DR.