Biomedical subjects

G Barja

Publications and source records attributed to G Barja.

At least 19 recordsLinked to original sources

PubMed2000

Double bond content of phospholipids and lipid peroxidation negatively correlate with maximum longevity in the heart of mammals.

Free radical damage is currently considered a main determinant of the rate of aging. Unsaturated fatty acids are the tissue macromolecules most sensitive to oxidative damage. Therefore, the presence of relatively low degrees of fatty acid unsaturation is expected in the tissues of longevous animals. In agreement with this prediction, fatty acid analyses of heart phospholipids in eight mammals ranging in maximum life span (MLSP) from 3.5 to 46 years showed that their total number of double bonds is negatively correlated with MLSP (r = -0.78, P < 0.02). The low double content of longevous mammals was not due to a low polyunsaturated fatty acid content. Instead, it was mainly due to a redistribution between types of polyunsaturated fatty acids from the highly unsaturated docosahexaenoic acid (22:6n-3) to the less unsaturated linoleic acid (18:2n-6) in longevous animals (r = -0.89, P < 0.003 for 22:6n-3 and r = 0.91, P < 0.002 for 18:2n-6 versus MLSP), where n = number of different animals in each species. This redistribution suggests that one of the mechanisms responsible for the low number of fatty acid double bonds is the presence of low desaturase activities in longevous animals, although other causing factors must be involved. In agreement with the low degree of fatty acid unsaturation of longevous mammals, the sensitivity to lipid peroxidation (r = -0.87; P < 0.005) and the in vivo lipid peroxidation (r = -0.86, P < 0.005) in the heart were also negatively correlated with MLSP across species. These results, together with previous ones obtained in rodents, birds, and humans, suggest that the low degree of tissue fatty acid unsaturation of longevous homeothermic animals could have been selected during evolution to protect the tissues against oxidative damage.

Aging↗

PubMed2000

Low fatty acid unsaturation: a mechanism for lowered lipoperoxidative modification of tissue proteins in mammalian species with long life spans.

Carbonyl compounds generated by the nonenzymatic oxidation of polyunsaturated fatty acids react with nucleophilic groups in proteins, leading to their modification. It has not been tested whether fatty acid unsaturation is related to steady-state levels of lipoxidation-derived protein modification in vivo. A low fatty acid unsaturation, hence a low protein lipoxidation, in tissues of longevous animals would be consistent with the free radical theory of aging, because membrane lipids increase their sensitivity to oxidative damage as a function of their degree of unsaturation. To evaluate the relationship between fatty acid composition, protein lipoxidation, and maximum life span (MLSP), we analyzed liver fatty acids and proteins from seven mammalian species, ranging in MLSP from 3.5 to 46 years. The results show that the peroxidizability index of fatty acids and the sensitivity to in vitro lipid peroxidation are negatively correlated with the MLSP. Based on gas chromatography and mass spectroscopy analyses, liver proteins of all these species contain malondialdehyde-lysine and Nepsilon-carboxymethyllysine adducts, two biomarkers of protein lipoxidation. The steady-state levels of malondialdehyde-lysine and Nepsilon-carboxymethyl lysine are directly related to the peroxidizability index and inversely related to the MLSP. We propose that a low degree of fatty acid unsaturation may have been selected in longevous mammals to protect their tissue lipids and proteins against oxidative damage while maintaining an appropriate environment for membrane function.

Animals↗

PubMed2000

Oxidative damage to mitochondrial DNA is inversely related to maximum life span in the heart and brain of mammals.

DNA damage is considered of paramount importance in aging. Among causes of this damage, free radical attack, particularly from mitochondrial origin, is receiving special attention. If oxidative damage to DNA is involved in aging, long-lived animals (which age slowly) should show lower levels of markers of this kind of damage than short-lived ones. However, this possibility has not heretofore been investigated. In this study, steady-state levels of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) referred to deoxyguanosine (dG) were measured by high performance liquid chromatography (HPLC) in the mitochondrial (mtDNA) and nuclear (nDNA) DNA from the heart of eight and the brain of six mammalian species ranging in maximum life span (MLSP) from 3.5 to 46 years. Exactly the same digestion of DNA to deoxynucleosides and HPLC protocols was used for mtDNA and nDNA. Significantly higher (three- to ninefold) 8-oxodG/dG values were found in mtDNA than in nDNA in all the species studied in both tissues. 8-oxodG/dG in nDNA did not correlate with MLSP across species either in the heart (r=-0.68; P<0.06) or brain (r = 0.53; P<0.27). However, 8-oxodG/dG in mtDNA was inversely correlated with MLSP both in heart (r=-0.92; P<0.001) and brain (r=-0.88; P<0.016) tissues following the power function y = a(.)x(b), where y is 8-oxodG/dG and x is the MLSP. This agrees with the consistent observation that mitochondrial free radical generation is also lower in long-lived than in short-lived species. The results obtained agree with the notion that oxygen radicals of mitochondrial origin oxidatively damage mtDNA in a way related to the aging rate of each species.-Barja, G., Herrero, A. Oxidative damage to mitochondrial DNA is inversely related to maximum life span in the heart and brain of mammals.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

A low degree of fatty acid unsaturation leads to lower lipid peroxidation and lipoxidation-derived protein modification in heart mitochondria of the longevous pigeon than in the short-lived rat.

Birds have a maximum longevity (MLSP) much greater than mammals of similar metabolic rate and body size. Thus, they are ideal models to identify longevity characteristics not linked to low metabolic rates. In this investigation, we show that the fatty acid double bond content of total lipids and phosphatidylcholine, phosphatidylethanolamine and cardiolipin fractions of heart mitochondria is intrinsically lower in pigeons (MLSP = 35 years) than in rats (MLSP = 4 years). This is mainly due to a lower content of the most highly unsaturated docosahexaenoic acid (22:6n-3) and in some fractions arachidonic acid (20:4n-6). The lower double bond content leads to a lower sensitivity to in vitro lipid peroxidation, and is associated with a lower concentration of lipid peroxidation products in vivo, and a lower level of malondialdehyde-lysine protein adducts in heart mitochondria of pigeons than rats. These results, together with those previously obtained in other species or tissues, suggest that a low degree of fatty acid unsaturation is a general characteristic of longevous homeothermic vertebrate animals both when they have low metabolic rates (mammals of large body size) or high metabolic rates (small sized birds). This constitutive trait helps to protect their tissues and mitochondria against lipid peroxidation and oxidative protein modification and can be a factor contributing to their slow rate of aging. The results also show, for the first time in a physiological model, that lipid peroxidizability is related to lipoxidative protein damage.

Aging↗

PubMed1999

8-oxo-deoxyguanosine levels in heart and brain mitochondrial and nuclear DNA of two mammals and three birds in relation to their different rates of aging.

Previous studies found that the rate of mitochondrial oxygen radical generation is lower in long-lived birds than in short-lived mammals. In the present study, the oxidative DNA damage marker 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in heart and brain mitochondrial (mtDNA) and nuclear DNA (nDNA) was compared between mammals and birds of approximately similar body size and metabolic rates; rats (maximum life span, MLSP = 4 years) vs pigeons (MLSP = 35 years), and mice (MLSP = 3.5 years) vs parakeets (MLSP = 21 years) or canaries (MLSP = 24 years). Lower steady-state 8-oxodG values were observed in all cases in the heart mtDNA in birds than in mammals. 8-oxodG levels were also lower in brain mtDNA in pigeons than in rats, in brain nDNA in canaries than in mice, and in heart nDNA in parakeets compared with mice. The rest of the comparisons did not show significant differences between species. These results taken together indicate that oxidative damage to DNA tends to be lower in birds (highly long-lived species) than in short-lived mammals, specially in the case of mtDNA. This is consistent with the low rate of mitochondrial oxygen radical generation observed in all long-lived species investigated up to date, birds or mammals, including the bird species studied here. The results also show that 8-oxodG steady-state levels are much higher in mtDNA than in nDNA in all the tissues (heart and brain) and species (birds and mammals) studied.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Effect of thyroid status on lipid composition and peroxidation in the mouse liver.

In order to analyze the possible relationship between metabolic rate and oxidative stress, OF1 female mice were rendered hyper- or hypothyroid for 4-5 weeks by administration of 0.0012% L-thyroxine (T4) or 0.05% 6-n-propyl-2-thiouracil (PTU), respectively, in their drinking water. Treatment with T4 resulted in increased basal metabolic rate measured by oxygen consumption and liver cytochrome oxidase activity without altering the glutathione redox system. Endogenous lipid peroxidation, sensitivity to lipid peroxidation and fatty acid unsaturation were decreased in the hyperthyroid group. Hypothyroidism also decreased phosphatidylcholine and cardiolipin fatty acid unsaturation but not in total lipids, and thus lipid peroxidation was not altered. Cardiolipin, a mainly mitochondrial lipid, was the most profoundly altered fraction by both hyper- and hypothyroidism. It is suggested that the lipid changes observed in hyperthyroid animals can protect them against an increased oxidative attack to tissue lipids due to their increased mitochondrial activities.

Animals↗

PubMed1999

Resveratrol, melatonin, vitamin E, and PBN protect against renal oxidative DNA damage induced by the kidney carcinogen KBrO3.

Free radical scavengers can protect against the genotoxicity induced by chemical carcinogens by decreasing oxidative damage. The protective effect of the antioxidants melatonin, resveratrol, vitamin E, butylated hydroxytoluene and 2-mercaptoethylamine, and the spin-trapping compound alpha-phenyl-N-tert-butyl nitrone (PBN) against oxidative DNA damage was studied in the kidney of rats treated with the kidney-specific carcinogen potassium bromate (KBrO3). KBrO3 was given to rats previously treated with melatonin, resveratrol, PBN, vitamin E, butylated hydroxytoluene, or 2-mercaptoethylamine. Oxidative damage to kidney DNA was estimated 6 hours afterwards by measuring 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxo8dG) referred to deoxyguanosine (dG) by means of high performance liquid chromatography with electrochemical-coulometric and ultraviolet detection. Levels of oxo8dG in the renal genomic DNA significantly increased by more than 100% after the KBrO3 treatment. This increase was completely abolished by the treatment with resveratrol and was partially prevented by melatonin, PBN and vitamin E. Resveratrol and PBN also prevented the increase in relative kidney weight induced by KBrO3. These results show that various different antioxidants and a free radical trap, working in either the water-soluble or the lipid-soluble compartments, can prevent the oxidative DNA damage induced in the kidney by the carcinogen KBrO3.

Animals↗

PubMed1999

Thyroid status modulates glycoxidative and lipoxidative modification of tissue proteins.

Steady state protein modification by carbonyl compounds is related to the rate of carbonyl adduct formation and the half-life of the protein. Thyroid hormones are physiologic modulators of both tissue oxidative stress and protein degradation. The levels of the glycation product N(epsilon)-fructoselysine (FL) and those of the oxidation products, N(epsilon)-(carboxymethyl)lysine (CML) and malondialdehyde-lysine (MDA-lys), identified by GC/MS in liver proteins, decreased significantly in hyperthyroid rats, as well as (less acutely) in hypothyroid animals. Immunoblotting of liver proteins for advanced glycation end-products (AGE) is in agreement with the results obtained by GC/MS. Cytosolic proteolytic activity against carboxymethylated foreign proteins measured in vitro was significantly increased in hypo- and hyperthyroidism. Oxidative damage to DNA, estimated as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxodG), did not show significant differences between groups. The results suggests that the steady state levels of these markers depend on the levels of thyroid hormones, presumably through their combined effects on the rates of protein degradation and oxidative stress, whereas DNA is more protected from oxidative damage.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Mitochondrial oxygen radical generation and leak: sites of production in states 4 and 3, organ specificity, and relation to aging and longevity.

Studies in heart and nonsynaptic brain mitochondria from two mammals and three birds show that complex I generates oxygen radicals in heart and nonsynaptic brain mitochondria in States 4 and 3, whereas complex III does it only in heart mitochondria and only in State 4. The increase in oxygen consumption during the State 4 to 3 transition is not accompanied by a proportional increase in oxygen radical generation. This will protect mitochondria and tissues during bursts of activity. Comparisons between young and old rodents do not show a consistent pattern of variation in mitochondrial oxygen radical production during aging. However, all the interspecies comparisons performed to date between different mammals, and between mammals and birds, agree that animals with high maximum longevities have low rates of mitochondrial oxygen radical production, irrespective of the value of their basal specific metabolic rate. The sites and mechanisms allowing this, the recently described low degree of membrane fatty acid unsaturation of longevous animals, and their relation to longevity and aging are discussed.

Aging↗

PubMed1999

Heart fatty acid unsaturation and lipid peroxidation, and aging rate, are lower in the canary and the parakeet than in the mouse.

Despite their high metabolic rates, birds have a much higher maximum longevity (MLSP) than mammals of similar body size, and thus represent ideal models for identifying longevity characteristics not linked to low metabolic rates. This study shows that the fatty acid double bond content of both canary (MLSP = 24 years) and parakeet (MLSP = 21 years) hearts is intrinsically lower than in mouse (MLSP = 3.5 years) heart. This is caused by a redistribution between types of unsaturated fatty acids, mainly due to a lower content of the most highly unsaturated docosahexaenoic acid (22:6n-3) in the two birds in relation to the mammal. The lower double bond content leads to a lower sensitivity to lipid peroxidation, and to a lower level of in vivo lipid peroxidation in the heart of parakeets and canaries than in that of mice. Similar results have been previously found comparing liver mitochondria of rats and pigeons and tissues of different mammalian species. All these results taken together suggest that a low degree of fatty acid unsaturation is a general characteristic of longevous homeothermic vertebrate animals, both when they have low metabolic rates (mammals of large body size) or high metabolic rates (the studied birds); this constitutive trait protects their tissues and organelles against free radical mediated lipid peroxidation, and can contribute to their slow aging rate.

Aging↗

PubMed1999

Effect of MPTP on brain mitochondrial H2O2 and ATP production and on dopamine and DOPAC in the striatum.

An experimental rat model of Parkinson's disease was established by injecting rats directly in the striatum with the neurotoxic agent 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In order to study the action mechanism of this neurotoxic agent, MPTP and its main metabolite 1-methyl-4-phenylpyridinium (MPP+) were also added to suspensions of pyruvate/malate-supplemented nonsynaptic brain mitochondria, and the rates of hydrogen peroxide and ATP production were measured. Intrastriatal administration of MPTP produced a pronounced decrease in striatal dopamine levels (p < 0.005) and a strong increase in 3,4-hydroxiphenylacetic acid/dopamine ratio (an indicator of dopamine catabolism; p < 0.005) in relation to controls, as evaluated by in situ microdialysis. MPTP addition to rat brain mitochondria increased hydrogen peroxide production by 90%, from 1.37+/-0.35 to 2.59+/-0.48 nanomoles of H2O2/minute . mg of protein (p < 0.01). The metabolite MPP+ produced a marked decrease on the rate of ATP production of brain mitochondria (p < 0.005). These findings support the mitochondria-oxidative stress-energy failure hypothesis of MPTP-induced brain neurotoxicity.

1-Methyl-4-phenylpyridinium↗

PubMed1998

Mitochondrial free radical production and aging in mammals and birds.

The mitochondrial rate of oxygen radical (ROS) production is negatively correlated with maximum life span potential (MLSP) in mammals following the rate of living theory. In order to know if this relationship is more than circumstantial, homeothermic vertebrates with MLSP different from that predicted by the body size and metabolic rate of the majority of mammals (like birds and primates) must be studied. Birds are unique because they combine a high rate of basal oxygen consumption with a high MLSP. Heart, brain, and lung mitochondrial ROS production and free radical leak (percent of total electron flow directed to ROS production) are lower in three species of birds of different orders than in mammals of similar body size and metabolic rate. This suggests that the capacity to show a low rate of ROS production is a general characteristic of birds. Using substrates and inhibitors specific for different segments of the respiratory chain, the main ROS generator site (responsible for those bird-mammalian differences) in state 4 has been localized at complexes I and III in heart mitochondria and only at complex I in nonsynaptic brain mitochondria. In state 3, complex I is the only generator in both tissues. The results also suggest that the iron-sulphur centers are the ROS generators of complex I. A general mechanism that allows pigeon mitochondria to show a low rate of ROS production can be the capacity to maintain a low degree of reduction of the ROS generator site. In heart mitochondria, this is supplemented with a low rate of oxygen consumption physiologically compensated with a comparatively higher heart size. A low rate of free radical production near DNA, together with a high rate of DNA repair, can be responsible for the slow rate of accumulation of DNA damage and thus the slow aging rate of longevous animals.

Aging↗

PubMed1998

H2O2 production of heart mitochondria and aging rate are slower in canaries and parakeets than in mice: sites of free radical generation and mechanisms involved.

Birds have a maximum longevity (MLSP) much higher than mammals of similar body size in spite of their high metabolic rates. In this study, State 4 and State 3 rates of H2O2 production were lower in canary (MLSP = 24 years) and parakeet (MLSP = 21 years) than in mouse (MLSP = 3.5 years) heart mitochondria. Studies using specific inhibitors of the respiratory chain indicate that free radical generation sites at Complexes I and III are responsible for these differences. Main mechanisms lowering H2O2 production in these birds are a low rate of mitochondrial oxygen consumption in the parakeet and a low mitochondrial free radical leak in the canary. Strong increases in H2O2 production during active respiration (State 3) released by addition of ADP to pyruvate/malate-supplemented mitochondria are avoided in three species because the free radical leak decreases during the transition from State 4 to State 3 respiration. These results, together with those previously obtained in pigeons and in various mammalian species, suggest that the rate of mitochondrial free radical production correlates better with the rate of aging and the MLSP than the metabolic rate. They also suggest that a low rate of mitochondrial H2O2 production is a general characteristic of birds, animals showing very slow aging rates.

Aging↗

PubMed1998

The rate of free radical production as a determinant of the rate of aging: evidence from the comparative approach.

The relationship of oxidative stress with maximum life span (MLSP) in different vertebrate species is reviewed. In all animal groups the endogenous levels of enzymatic and non-enzymatic antioxidants in tissues negatively correlate with MLSP and the most longevous animals studied in each group, pigeon or man, show the minimum levels of antioxidants. A possible evolutionary reason for this is that longevous animals produce oxygen radicals at a low rate. This has been analysed at the place where more than 90% of oxygen is consumed in the cell, the mitochondria. All available work agrees that, across species, the longer the life span, the lower the rate of mitochondrial oxygen radical production. This is true even in animal groups that do not conform to the rate of living theory of aging, such as birds. Birds have low rates of mitochondrial oxygen radical production, frequently due to a low free radical leak in their respiratory chain. Possibly the low rate of mitochondrial oxygen radical production of longevous species can decrease oxidative damage at targets important for aging (like mitochondrial DNA) that are situated near the places of free radical generation. A low rate of free radical production can contribute to a low aging rate both in animals that conform to the rate of living (metabolic) theory of aging and in animals with exceptional longevities, like birds and primates. Available research indicates there are at least two main characteristics of longevous species: a high rate of DNA repair together with a low rate of free radical production near DNA. Simultaneous consideration of these two characteristics can explain part of the quantitative differences in longevity between animal species.

Aging↗

PubMed1998

Localization at complex I and mechanism of the higher free radical production of brain nonsynaptic mitochondria in the short-lived rat than in the longevous pigeon.

Free radical production and leak of brain nonsynaptic mitochondria were higher with pyruvate/malate than with succinate in rats and pigeons. Rotenone, antimycin A, and myxothiazol maximally stimulated free radical production with pyruvate/malate but not with succinate. Simultaneous treatment with myxothiazol plus antimycin A did not decrease the stimulated rate of free radical production brought about independently by any of these two inhibitors with pyruvate/malate. Thenoyltrifluoroacetone did not increase free radical production with succinate. No free radical production was detected at Complex IV. Free radical production and leak with pyruvate/malate were higher in the rat (maximum longevity 4 years) than in the pigeon (maximum longevity 35 years). These differences between species disappeared in the presence of rotenone. The results localize the main free radical production site of nonsynaptic brain mitochondria at Complex I. They also suggest that the low free radical production of pigeon brain mitochondria is due to a low degree of reduction of Complex I in the steady state in this highly longevous species.

Animals↗

PubMed1998

Endotoxin increases oxidative injury to proteins in guinea pig liver: protection by dietary vitamin C.

Current information suggests that oxidative damage plays a key role in septic shock induced by endotoxin. This raises the possibility that dietary antioxidant vitamins could protect against endotoxin damage. In this study, the effects of endotoxin administration on protein and lipid oxidative damage and endogenous antioxidants were studied in the liver of guinea pigs previously supplemented with marginal or optimum levels of dietary vitamin C, vitamin E or both. Vitamins C and E inhibited in vitro lipid peroxidation in endotoxin-treated animals. Endotoxin significantly increased oxidative damage to liver proteins in animals receiving low doses of both vitamins, a result described here for the first time. This increase was totally prevented in guinea pigs supplemented with vitamin C alone or in combination with vitamin E, a treatment which strongly increased liver ascorbate. Vitamin C caused small significant increases in superoxide dismutase and glutathione, increased uric acid, and synergically increased alpha-tocopherol levels in vitamin E-supplemented animals treated with endotoxin. The results show that dietary vitamin C protects against endotoxin-induced oxidative damage to proteins in the guinea pig liver. This seems mainly due to a direct protective effect of the increased hepatic ascorbate levels present in vitamin C-supplemented animals.

Animals↗

PubMed1998

Mitochondrial membrane peroxidizability index is inversely related to maximum life span in mammals.

The oxidative stress theory of aging predicts a low degree of fatty acid unsaturation in tissues of longevous animals, because membrane lipids increase their sensitivity to oxidative damage as a function of their unsaturation. Accordingly, the fatty acids analyses of liver mitochondria from eight mammals, ranging in maximum life span from 3.5 to 46 years, show that the total number of double bonds and the peroxidizability index are negatively correlated with maximum life span (r = -0. 88, P < 0.003; r = -0.87, P < 0.004, respectively). This is not due to a low content of unsaturated fatty acids in longevous animals, but mainly to a redistribution between kinds of the polyunsaturated n-3 fatty acids series, shifting from the highly unsaturated docosahexaenoic acid (r = -0.89, P < 0.003) to the less unsaturated linolenic acid (r = 0.97, P < 0.0001). This redistribution pattern strongly suggests the presence of a constitutively low delta6-desaturase activity in longevous animals (r = -0.96, P < 0.0001). Thus, it may be proposed that, during evolution, a low degree of fatty acid unsaturation in liver mitochondria may have been selected in longevous mammals in order to protect the tissues against oxidative damage, while maintaining an appropriate environment for membrane function.

Aging↗

PubMed1997

Sites and mechanisms responsible for the low rate of free radical production of heart mitochondria in the long-lived pigeon.

Basal (substrate alone) and maximum rates of H2O2 production, oxygen consumption and free radical leak in the respiratory chain were higher in heart mitochondria of the short-lived rat (4 years) than in the long-lived pigeon (35 years). This suggests that the low free radical production of pigeon heart mitochondria is due in part to both a low electron flow and a low percent leak of electrons out of sequence in the respiratory chain. Thenoyltrifluoroacetone did not increase H2O2 production with succinate either in rats or pigeons. Mitochondrial H2O2 production was higher with pyruvate/malate than with succinate in both animal species. Rotenone and antimycin A increased H2O2 production with pyruvate/malate to the maximum levels observed in each species. Addition of myxothiazol to antimycin A-treated mitochondria supplemented with pyruvate/malate decreased H2O2 production in both species. All the combinations of inhibitors added with pyruvate/malate resulted in higher rates of H2O2 production in rats than in pigeons. When succinate instead of pyruvate/malate was used as substrate, rotenone and thenoyltrifluoroacetone decreased mitochondrial H2O2 production in the rat and did not change it in the pigeon. The results indicate that Complexes I and III are the main H2O2 generators of heart mitochondria in rats and pigeons and that both Complexes are responsible for the low H2O2 production of the bird. p-Chloromercuribenzoate and ethoxyformic anhydride strongly inhibited the H2O2 production induced by rotenone with pyruvate/malate in both species. This suggests that the free radical generator of Complex I is located after the ferricyanide reduction site, between the ethoxyformic and the rotenone-sensitive sites.

Aging↗