Metabolomics reveals that fittest trail runners show a better adaptation of bioenergetic pathways.

OBJECTIVES: To analyze the effect in the blood metabolome of trail running, a demanding sport that takes place in the natural environment, places considerable strain on both muscles and joints. While metabolic responses to aerobic exercise have been analyzed in-depth, few studies have focused on trail running. DESIGN: Observational study to analyze changes in 35 different metabolites - representative of aerobic exercise-induced by a simulated 21-km trail race with an uphill gradient of 1400 m. METHODS: We performed a semiquantitative metabolomics study consisting of capillary blood microsampling and targeted screening with liquid chromatography and mass spectrometry to analyze, in 33 licensed athletes, changes concerning 35 metabolites. RESULTS: We observed significant changes in many metabolites, including increased acetyl-carnitine and taurine concentrations (false discovery rate-corrected paired t-test P value 1.63 × 10-13, and P value 5.021 × 10-12, respectively) and decreased carnitine and proline concentrations (P value 6.33 × 10-10, and P value 1.21 × 10-9, respectively). Metabolic responses to trail running were largely independent of sex but were influenced by the level of training, with runners with a higher level showing resistance to exercise-induced changes in taurine, 1-methyl histidine, acetyl-carnitine, and hypoxanthine concentrations. Performance (measured as race time) was inversely correlated with changes in specific metabolites (including taurine, serotonin, and hypoxanthine) and directly correlated with increases in glutathione. CONCLUSIONS: Our findings demonstrate the usefulness of metabolomics studies for analyzing exercise-induced physiological changes and show individual differences associated with the level of training and performance.

Faecal bacterial and short-chain fatty acids signature in hypercholesterolemia.

Gut microbiota has been suggested to affect lipid metabolism. The objective of this study was to characterize the faecal microbiota signature and both short chain fatty acids (SCFAs) and bile acids (BA) profile of hypercholesterolemic subjects. Microbiota composition, SCFAs, BA and blood lipid profile from male volunteers with hypercholesterolemia (HC) and normocholesterolemia (NC) were determined by 16S rDNA sequencing, HPLC, GC and NMR, respectively. HC subjects were characterized by having lower relative abundance of Anaeroplasma (0.002% vs 0.219%, p-value = 0.026) and Haemophilus (0.041% vs 0.078%, p-value = 0.049), and higher of Odoribacter (0.51% vs 0.16%; p-value = 0.044). Correlation analysis revealed that Anaeroplasma and Haemophilus were associated to an unfavourable lipid profile: they correlated negatively to cholesterol and triglycerides related biomarkers and the ratio total to high density lipoprotein (HDL) cholesterol, and positively to HDL size. Odoribacter displayed an opposite behaviour. Faecal SCFAs profile revealed higher abundance of isobutyric (2.76% vs 0.82%, p-value = 0.049) and isovaleric acid (1.32% vs 0.06%, p-value = 0.016) in HC. Isobutyric acid correlated positively with Odoribacter and lipid parameters indicative of an unfavourable profile. BA profile did not show differences between groups. It was concluded that HC subjects showed a particular faecal bacterial signature and SCFAs profile associated with their lipid profile.

Psoriasis, metabolic syndrome and cardiovascular risk factors. A population-based study.

BACKGROUND: Psoriasis is a very prevalent systemic chronic inflammatory disease. Major cardiovascular events are the main cause of mortality in these patients which suggests an association between psoriasis and traditional cardiovascular risk factors. OBJECTIVE: To identify classic cardiovascular risk factors and metabolic syndrome (MS) in patients with psoriasis, their possible association with its severity and compare it with the non-psoriatic population. METHODS: This is an observational and cross-sectional population study in Lleida (Spain) from a joint hospital/primary care database. RESULTS: The database comprised 398 701 individuals. There were 6868 cases registered as psoriasis (1.7%), and 499 of them (7.3%) were classified as moderate-severe psoriasis. Patients with psoriasis had a higher prevalence of traditional cardiovascular risk factors than non-psoriatic population: diabetes mellitus 2 (13.9% vs 7.4%, OR 2.01), dyslipidaemia (28.8% vs 17.4%, OR 1.92), arterial hypertension (31.2% vs 19.0%, OR 1.93), obesity (33.7% vs 28.1%, OR 1.30), altered fasting basal glycaemia (21.4% vs 15.1%, OR 1.54), low cholesterol HDL (38.1% vs 32.3%, OR 1.29), hypertriglyceridaemia (45.7% vs 35.2%, OR 1.55) and high waist circumference (75.7% vs 72.3%, OR 1.19). MS was more prevalent in psoriatic patients (28.3% vs 15.1%, OR 2.21), and cardiovascular risk factors were similar between psoriasis severity groups. Psoriatic patients had a higher prevalence of ischaemic heart disease (3.3% vs 1.8%, OR 1.87) and vascular cerebral accidents (1.8% vs 1.2%, OR 1.55). A model for MS showed a significant nonlinear relationship with age and sex and significant differences between patients with and without psoriasis. CONCLUSION: We found statistically significant differences in relation to the prevalence of cardiovascular risk factors, MS and major cardiovascular events in psoriatic patients. However, differences were not seen between psoriasis severity groups. Our work reinforces the need for a multidisciplinary approach and close monitoring of cardiovascular risk factors in these patients to prevent a cardiovascular event.

The gut mycobiome composition is linked to carotid atherosclerosis.

The mycobiotic component of the microbiota comprises an integral, yet under-researched, part of the gastrointestinal tract. Here, we present a preliminary study of the possible contribution of gut mycobiota to sub-clinical atherosclerosis in a well-characterised group of obese and non-obese subjects in association with the Framingham Risk Score (FRS) and carotid intima-media thickness (cIMT). From all taxa identified, the relative abundance of the phylum Zygomycota, comprising the family Mucoraceae and genus Mucor, was negatively associated with cIMT and this association remained significant after controlling for false discovery rate. Obese subjects with detectable Mucor spp. had a similar cardiovascular risk profile as non-obese subjects. Interestingly, the relative abundance of Mucor racemosus was negatively associated both with FRS and cIMT. Partial least square discriminant analyses modelling, evaluating the potential relevance of gut mycobiota in patients stratified by mean values of cIMT, showed that even a 1 component model had a high accuracy (0.789), with a high R2 value (0.51). Variable importance in projection scores showed that M. racemosus abundance had the same impact in the model as waist-to-hip ratio, high-density lipoprotein-cholesterol, fasting triglycerides or fasting glucose, suggesting that M. racemosus relative abundance in the gut may be a relevant biomarker for cardiovascular risk.

Activation of sirtuin 1 as therapy for the peroxisomal disease adrenoleukodystrophy.

Oxidative stress and mitochondrial failure are prominent factors in the axonal degeneration process. In this study, we demonstrate that sirtuin 1 (SIRT1), a key regulator of the mitochondrial function, is impaired in the axonopathy and peroxisomal disease X-linked adrenoleukodystrophy (X-ALD). We have restored SIRT1 activity using a dual strategy of resveratrol treatment or by the moderate transgenic overexpression of SIRT1 in a X-ALD mouse model. Both strategies normalized redox homeostasis, mitochondrial respiration, bioenergetic failure, axonal degeneration and associated locomotor disabilities in the X-ALD mice. These results indicate that the reactivation of SIRT1 may be a valuable strategy to treat X-ALD and other axonopathies in which the control of redox and energetic homeostasis is impaired.

Impaired mitochondrial oxidative phosphorylation in the peroxisomal disease X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is an inherited metabolic disorder of the nervous system characterized by axonopathy in spinal cords and/or cerebral demyelination, adrenal insufficiency and accumulation of very long-chain fatty acids (VLCFAs) in plasma and tissues. The disease is caused by malfunction of the ABCD1 gene, which encodes a peroxisomal transporter of VLCFAs or VLCFA-CoA. In the mouse, Abcd1 loss causes late onset axonal degeneration in the spinal cord, associated with locomotor disability resembling the most common phenotype in patients, adrenomyeloneuropathy. We have formerly shown that an excess of the VLCFA C26:0 induces oxidative damage, which underlies the axonal degeneration exhibited by the Abcd1(-) mice. In the present study, we sought to investigate the noxious effects of C26:0 on mitochondria function. Our data indicate that in X-ALD patients' fibroblasts, excess of C26:0 generates mtDNA oxidation and specifically impairs oxidative phosphorylation (OXPHOS) triggering mitochondrial ROS production from electron transport chain complexes. This correlates with impaired complex V phosphorylative activity, as visualized by high-resolution respirometry on spinal cord slices of Abcd1(-) mice. Further, we identified a marked oxidation of key OXPHOS system subunits in Abcd1(-) mouse spinal cords at presymptomatic stages. Altogether, our results illustrate some of the mechanistic intricacies by which the excess of a fatty acid targeted to peroxisomes activates a deleterious process of oxidative damage to mitochondria, leading to a multifaceted dysfunction of this organelle. These findings may be of relevance for patient management while unveiling novel therapeutic targets for X-ALD.

Skeletal muscle uncoupling-induced longevity in mice is linked to increased substrate metabolism and induction of the endogenous antioxidant defense system.

Ectopic expression of uncoupling protein 1 (UCP1) in skeletal muscle (SM) mitochondria increases lifespan considerably in high-fat diet-fed UCP1 Tg mice compared with wild types (WT). To clarify the underlying mechanisms, we investigated substrate metabolism as well as oxidative stress damage and antioxidant defense in SM of low-fat- and high-fat-fed mice. Tg mice showed an increased protein expression of phosphorylated AMP-activated protein kinase, markers of lipid turnover (p-ACC, FAT/CD36), and an increased SM ex vivo fatty acid oxidation. Surprisingly, UCP1 Tg mice showed elevated lipid peroxidative protein modifications with no changes in glycoxidation or direct protein oxidation. This was paralleled by an induction of catalase and superoxide dismutase activity, an increased redox signaling (MAPK signaling pathway), and increased expression of stress-protective heat shock protein 25. We conclude that increased skeletal muscle mitochondrial uncoupling in vivo does not reduce the oxidative stress status in the muscle cell. Moreover, it increases lipid metabolism and reactive lipid-derived carbonyls. This stress induction in turn increases the endogenous antioxidant defense system and redox signaling. Altogether, our data argue for an adaptive role of reactive species as essential signaling molecules for health and longevity.

Atherosclerosis prevention by nutritional factors: a meta-analysis in small animal models.

BACKGROUND AND AIMS: Atherosclerosis prevention in small laboratory models has been used as a preclinical stage in the development of functional foods with claimed antiatherogenic properties. However, a high heterogeneity of experimental atherosclerosis models as well as species-specific differences in lipoprotein metabolism could limit the usefulness of these developments. To solve this, we have performed a meta-analysis on the effects of nutritional complements (i.e. less than 2% of diet) with potential antiatherogenic properties in mice, rabbits and hamsters, and compared the outcomes with those obtained in humans. METHODS AND RESULTS: A meta-analysis comprising works dealing with dietary prevention of experimental atherosclerosis (i.e. macroscopic and/or pathological evidences of atheromatosis in aorta) has been performed (n = 110 works). Quality criteria were applied resulting in selection of 16 works comprising 511 animals. Despite high heterogeneity, there is a significant effect of nutritional interventions reducing atheroma globally (mean effect 24.38% (95% CI: 13.24-35.51%) of prevention). In mouse studies (20.64% (95% CI: 8.38-32.90%)) and in rabbits (40.48% (95% CI: 6.73-74.23%)) this effect was significant, in contrast with hamster-based works (95% CI: 13.66-49.48%). Meta-regression showed that reduction of atheroma plaque formation was not linked to changes either in total circulating cholesterol or LDL cholesterol levels. CONCLUSION: Nutritional addition of selected compounds significantly prevents experimental atheromatosis, but the reproduction of positive effects observed in humans was very limited. These analyses reinforce the need for adequate standardization of atherosclerosis studies in preclinical models and for human intervention trials.

Fiebre reumática: entidad subyacente en un caso de amigdalitis / Rheumatic fever: underlying entity in acase of tonsillitis

La fiebre reumática, condición cuya presencia había disminuido en países desarrollados, presenta un cierto incremento de su incidencia en los últimos años. Por tanto, es importante tener presente su etiología, clínica y criterios diagnósticos ante faringoamigdalitis recidivantes y/o artropatías no filiadas. El debate en este ámbito se centra en las medidas de prevención secundaria, que serían la única intervención efectiva en países en vías de desarrollo. Se presenta el caso de una paciente de 34 años de edad con amigdalitis purulenta de repetición. Ante la falta de respuesta a antibioticoterapia inicial con cefalosporinas de segunda generación y posteriormente eritromicina, se procedió a toma de cultivo amigdalar y analítica, que facilitaron la clave sobre el diagnóstico final, fiebre reumática

The prevalence of rheumatic fever had decreased in developed countries. However, its incidence has recently increased. Therefore, it is essential to keep its etiology, clinical manifestations and diagnostic criteria in mind in cases of recurrent pharyngotonsillitis and/or arthropathies of unknown origin. The case of a 34-year-old woman is presented. After several episodes of purulent amygdalitis, refractory to cephalosporin and erythromycin treatment, a tonsil culture and biochemical parameters gave the final diagnosis of rheumatic fever

Effects of fasting on oxidative stress in rat liver mitochondria.

While moderate caloric restriction has beneficial effects on animal health state, fasting may be harmful. The present investigation was designed to test how fasting affects oxidative stress, and to find out whether the effects are opposite to those previously found in caloric restriction studies. We have focused on one of the main determinants of aging rate: the rate of mitochondrial free radical generation. Different parameters related to lipid and protein oxidative damage were also analyzed. Liver mitochondria from rats subjected to 72 h of fasting leaked more electrons per unit of O(2) consumed at complex III, than mitochondria from ad libitum fed rats. This increased leak led to a higher free radical generation under state 3 respiration using succinate as substrate. Regarding lipids, fasting altered fatty acid composition of hepatic membranes, increasing the double bond and the peroxidizability indexes. In accordance with this, we observed that hepatic membranes from the fasted animals were more sensitive to lipid peroxidation. Hepatic protein oxidative damage was also increased in fasted rats. Thus, the levels of oxidative modifications, produced either indirectly by reactive carbonyl compounds (N(epsilon)-malondialdehyde-lysine), or directly through amino acid oxidation (glutamic and aminoadipic semialdehydes) were elevated due to the fasting treatment in both liver tissue and liver mitochondria. The current study shows that severe food deprivation increases oxidative stress in rat liver, at least in part, by increasing mitochondrial free radical generation during state 3 respiration and by increasing the sensitivity of hepatic membranes to oxidative damage, suggesting that fasting and caloric restriction have different effects on liver mitochondrial oxidative stress.

Effect of experimental and cold exposure induced hyperthyroidism on H2O2 production and susceptibility to oxidative stress of rat liver mitochondria.

To investigate the iodothyronine role in liver responses to cold, we examined metabolic and oxidative mitochondrial changes in cold-exposed, T3-treated, and T4-treated rats, which exhibit different T4 serum levels. All treatments increased mitochondrial respiration which reached the highest and lowest values after T3 and cold treatment, respectively. The T3- and T4-induced changes agreed with the respective increases in Complex IV activities, while those elicited by cold were inconsistent with increased activities of respiratory complexes. Mitochondrial capacity to produce H2O2 was the highest in T3-treated rats, whereas it was similar in T4-treated and cold-exposed rats. The effects of respiratory inhibitors suggested that T3 and T4 mainly increase the mitochondrial content of autoxidizable electron carrier of Complex I and Complex III, respectively. The indices of oxidative modifications of proteins exhibited increases consistent with the treatment effects on H2O2 production. The increases in indices of lipid peroxidation were also dependent on changes in lipid composition. The increased protein damage in treatment groups was confirmed using immunoblotting analysis, which also showed oxidative damage in a 133 kDa fraction, which was not expressed in T3-treated rats. Antioxidant levels were not related to the extent of oxidative damage as only mitochondrial GSH levels decreased in T3-treated rats. Mitochondrial susceptibility to in vitro oxidative challenge and Ca2+-induced swelling was increased by all treatments, but was the highest in T3-treated rats. In the whole, our results indicate T3 as main responsible for the changes in the mitochondrial population associated with cold exposure. However, a significant role is also played by T4, which appears to acts mainly modulating T3 effects, but also inducing some effects different from the T3 ones.

Lesión oxidativa de proteínas de hígado y corazón de rata durante el proceso de envejecimiento / Protein oxidative damage in rat liver and heart during the ageing process

Objetivos: el proceso de envejecimiento afecta a todos los organismos y es de suponer que sus mecanismos básicos esten conservados entre especies. La oxidación de proteínas se ha propuesto como uno de estos mecanismos básicos enlazando los radicales derivados del oxígeno con el proceso básico de envejecimiento. Así, si la lesión oxidativa de proteínas esta implicada en el envejecimiento, los animales con edades avanzadas deberían presentar valores basales elevados de lesión proteínica en comparación con animales más jóvenes. Sin embargo, la información disponible sobre esta predicción es limitada considerando la utilización de marcadores químicos específicos. Material y método: en este estudio, la concentración basal de diferentes marcadores de lesión proteínica (oxidación [semialdehídos glutámico y aminoadípico], glucoxidación [carboxietil-lisina], mixto de gluco y lipoxidación [carboximetil-lisina] y lipoxidación [malondialdehído-lisina]), así como el perfil de ácidos grasos de membrana, han sido determinados en el hígado y corazón de ratas macho adultas jóvenes (8 meses) y edad avanzada (30 meses). Resultados: los resultados mostraron incrementos significativos de los marcadores de oxidación y glucoxidación en el grupo de animales de 30 meses tanto en hígado como en corazón. Con relación a la lesión lipoxidativa, también se detectó un aumento significativo de ésta en el grupo de edad avanzada, probablemente asociado al incremento del índice de dobles enlaces y peroxidabilidad mostrados por las membranas celulares del hígado y corazón. Comparativamente, el corazón mostró grados de lesión oxidativa y lipoxidativa significativamente superiores a los del hígado. Los niveles de lesión glucoxidativa fueron superiores en hígado que en corazón. Asimismo, el corazón mostró mayor sensibilidad al envejecimiento, como lo demuestran los mayores incrementos porcentuales en lesión oxidativa, gluco y lipoxidativa. Conclusiones: estos resultados, en el contexto de la teoría del envejecimiento basada en el estrés oxidativo, además de poner de manifiesto las diferencias existentes entre órganos, refuerzan el papel del grado de insaturación de membrana, así como de los mecanismos homeostáticos que regulan el valor basal de modificación oxidativa en dicho proceso biológico

Objectives: ageing affects all organisms and its basic mechanisms can be expected to be conserved across species. Protein oxidation has been proposed as one of the basic mechanisms linking oxygen radicals with the basic ageing process. If oxidative damage to proteins is involved in ageing, aged animals should show higher steady-state levels of specific markers of this kind of damage than younger adult animals. However, the evidence available on this prediction is limited when the use of specific chemical markers is considered. Material and method: we measured steady-state levels of markers of different kinds of protein damage-oxidation (glutamic and aminoadipic semialdehydes), glycoxidation (carboxyethyl-lysine), mixed glyco- and lipoxidation (carboxymethyl-lysine), and lipoxidation (malondialdehydelysine)-, as well as fatty acid profile in the livers and hearts of young adult (8 months old) and aged (30 months old) male rats. Results: oxidative and glycoxidative markers were significantly increased in both the liver and heart of aged rats. Lipoxidation damage was also significantly increased in aged rats. This result was probably associated with the significantly increased double bond and peroxidizability indexes found in liver and heart cell membranes. Steady-state levels of oxidation and lipoxidation damage were significantly higher in the heart than in the liver. In contrast, glycoxidation damage was greater in the liver than in the heart. Accumulation rates of protein damage were higher in the heart than in the liver during aging. Conclusions: in the context of the oxidative stress theory of ageing, these results reveal differences between organs and reinforce the role of membrane unsaturation as well as the homeostatic mechanisms that maintain the steady-state level of protein damage in this biological process

Effect of insulin and growth hormone on rat heart and liver oxidative stress in control and caloric restricted animals.

In order to know if insulin-like signalling is involved in the control of oxidative stress in mammalian tissues in relation to aging, ad libitum-fed and caloric restricted Wistar rats were treated during 2 weeks with GH and insulin. The most consistent effect of the hormonal treatments was an increase in plasma IGF-1 levels. Caloric restriction during 6 weeks decreased ROS generation and oxidative DNA damage in heart mitochondria and this was reversed by insulin treatment. The decrease in oxidative damage to liver nuclear DNA induced by caloric restriction was also reversed by GH and insulin. In the liver, however, insulin and GH decreased mitochondrial ROS generation while they increased oxidative damage to mitochondrial DNA. GH and insulin decreased three different markers of oxidative modification of liver proteins, while they increased lipoxidation-dependent markers. This last result is related to the increase in phospholipid unsaturation induced in the liver by both hormones. The results suggest that the idea that insulin-like signalling controls oxidative stress in mammals cannot be generalized since both prooxidant and protective effects of GH and insulin are observed depending on the particular parameter and tissue selected.

Cold-induced hyperthyroidism produces oxidative damage in rat tissues and increases susceptibility to oxidants.

In this work, we investigated whether cold exposure-induced hyperthyroidism increases oxidative damage and susceptibility to oxidants of rat liver, heart and skeletal muscle. All tissues exhibited gradual increases in hydroperoxide and protein-bound carbonyl levels. Glutathione peroxidase activity increased in all tissues after 2 days and further increased in the muscle after 10 days of cold exposure. Liver glutathione reductase activity increased after 10 days of cold exposure, while heart and muscle activities were not modified. Vitamin E levels were not affected by cold, while coenzyme Q9 and coenzyme Q10 levels decreased in heart and muscle after 2-day cold exposure and were not further modified after 10 days. Liver coenzyme Q9 levels increased after 2 days whereas coenzyme Q10 levels increased after 10 days in the cold. The whole antioxidant capacity was lowered, while parameters positively correlated with susceptibility to oxidants were increased by cold. Lipid fatty acid composition was modified in all tissues. In particular, fatty acid unsaturation degree increased in heart and muscle. Cytochrome oxidase activity increased, suggesting an increased content of hemoproteins, which are able to generate .OH radical. This view was supported by the observation that the tissue susceptibility to H(2)O(2) treatment, which is strongly correlated to iron-ligand content, increased after cold exposure. In this frame, it is apparent that the increase in oxidative capacity, necessary for homeotherm survival in low temperature environments, has potential harmful effects, because it results in increased susceptibility to oxidative challenge.

Protein modification by advanced Maillard adducts can be modulated by dietary polyunsaturated fatty acids.

Advanced Maillard adducts, such as N epsilon-(carboxymethyl)lysine and N epsilon-(carboxyethyl)lysine, can be formed efficiently in vitro from both peroxidation of polyunsaturated fatty acids and glycolysis intermediates. In an attempt to differentiate the in vivo influence of the two pathways in these modifications, Wistar rats were chronically fed with specially designed diets rich in saturated or unsaturated fats. The degree of fatty acid unsaturation of all analysed organs (liver, kidney, brain) was altered by these dietary stresses. Protein glycoxidative and lipoxidative modifications were measured by GC/MS. In accordance with fatty acid profiles, concentrations of N epsilon-(malondialdehyde)lysine in these tissues were significantly increased in animals fed the unsaturated fat diet. In contrast, N epsilon-(carboxymethyl)lysine and N epsilon-(carboxyethyl)lysine concentrations were strongly dependent on the tissue analysed; although the unsaturated fat diet increased their levels significantly in brain, levels were unchanged in kidney and decreased in liver. These later results could be interpreted on the basis that polyunsaturated fatty acids decrease the expression of several glycolytic enzymes in liver. Globally, these data suggest that tissue-specific metabolic characteristics play a key role in the degree of cellular protein modification by Maillard reactions, e.g. by modulation of the concentration of glycolysis intermediates or via specific defensive systems in these organs.

Influence of hyper- and hypothyroidism on lipid peroxidation, unsaturation of phospholipids, glutathione system and oxidative damage to nuclear and mitochondrial DNA in mice skeletal muscle.

While the biochemical literature on free radical metabolism is extensive, there is little information on the endocrine control of tissue oxidative stress, and in the case of thyroid hormones it is mainly limited to liver tissue and to short-term effects on a few selected biochemical parameters. In this investigation, chronic hypothyroidism and hyperthyroidism were successfully induced in mice, and various oxidative-stress-related parameters were studied in skeletal muscle. In vivo and in vitro lipid peroxidation significantly increased in hyperthyroidism and did not change in the hypothyroid state. The fatty acid composition of the major phospholipid classes was affected by thyroid hormones, leading to a significant decrease in total fatty acid unsaturation both in hypothyroid and hyperthyroid muscle in phosphatidylcholine and phosphatidylethanolamine fractions. In cardiolipin, however, the double bond content significantly increased as a function of thyroid status, leading to a 2.7 fold increase in the peroxidizability index from euthyroid to hyperthyroid muscle. Cardiolipin content was also directly and significantly related to thyroid state across the three groups. Glutathione system was not modified by thyroid state. The oxidative damage marker 8-oxo-7,8-dihydro-2'-deoxyguanosine did not change in mitochondrial DNA, and decreased in genomic DNA both in hypothyroid and hyperthyroid muscle. The results indicate that chronic alterations in thyroid status specially affect oxidative damage to lipids in skeletal muscle, with a probably stronger effect on mitochondrial membranes, whereas the cytosolic redox potential and DNA are better protected possibly due to homeostatic compensatory reactions on the long-term.

Correlation of fatty acid unsaturation of the major liver mitochondrial phospholipid classes in mammals to their maximum life span potential.

Free radical damage is considered a determinant factor in the rate of aging. Unsaturated fatty acids are the tissue macromolecules that are most sensitive to oxidative damage. Therefore, the presence of low proportions of fatty acid unsaturation is expected in the tissues of long-lived animals. Accordingly, the fatty acid compositions of the major liver mitochondrial phospholipid classes from eight mammals, ranging in maximum life span potential (MLSP) from 3.5 to 46 yr, show that the total number of double bonds is inversely correlated with MLSP in both phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) (r = 0.757, P < 0.03, and r = 0.862, P < 0.006, respectively), but not in cardiolipin (P = 0.323). This is due not to a low content of unsaturated fatty acids in long-lived animals, but mainly to a redistribution between kinds of fatty acids on PtdCho and PtdEtn, shifting from arachidonic (r = 0.911, P < 0.002, and r = 0.681, P = 0.05, respectively), docosahexaenoic (r = 0.931 and r = 0.965, P < 0.0001, respectively) and palmitic (r = 0.944 and r = 0.974, P < 0.0001, respectively) acids to linoleic acid (r = 0.942, P < 0.0001, for PtdCho; and r = 0.957, P < 0.0001, for PtdEtn). For cardiolipin, only arachidonic acid showed a significantly inverse correlation with MLSP (r = 0.904, P < 0.002). This pattern strongly suggests the presence of a species-specific desaturation pathway and deacylation-reacylation cycle in determining the mitochondrial membrane composition, maintaining a low degree of fatty acid unsaturation in long-lived animals.

Effect of the degree of fatty acid unsaturation of rat heart mitochondria on their rates of H2O2 production and lipid and protein oxidative damage.

Previous comparative studies have shown that long-lived animals have lower fatty acid double bond content in their mitochondrial membranes than short-lived ones. In order to ascertain whether this trait protects mitochondria by decreasing lipid and protein oxidation and oxygen radical generation, the double bond content of rat heart mitochondrial membranes was manipulated by chronic feeding with semi-purified AIN-93G diets rich in highly unsaturated (UNSAT) or saturated (SAT) oils. UNSAT rat heart mitochondria had significantly higher double bond content and lipid peroxidation than SAT mitochondria. They also showed increased levels of the markers of protein oxidative damage malondialdehyde-lysine, protein carbonyls, and N(e)-(carboxymethyl)lysine adducts. Basal rates of mitochondrial oxygen radical generation were not modified by the degree of fatty acid unsaturation, but the rates of H2O2 generation stimulated by antimycin A were higher in UNSAT than in SAT mitochondria. These results demonstrate that increasing the degree of fatty acid unsaturation of heart mitochondria increases oxidative damage to their lipids and proteins, and can also increase their rates of mitochondrial oxygen radical generation in situations in which the degree of reduction of Complex III is higher than normal. These observations strengthen the notion that the relatively low double bond content of the membranes of long-lived animals could have evolved to protect them from oxidative damage.