A comparative study of free radicals in vertebrates—II. Nonenzymatic antioxidants and oxidative stress (original) (raw)
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Protection against oxidative stress in liver of four different vertebrates
The Journal of Experimental Zoology, 1999
The possible relation between respiratory capacity and antioxidant capacity and susceptibility to oxidative stress of the liver has been investigated in Rattus norvegicus, Gallus gallus domesticus, Lacerta s. sicula, and Rana esculenta. Accordingly, we measured oxygen consumption and cytochrome oxidase activity, glutathione peroxidase and glutathione reductase activity and overall antioxidant capacity, and lipid peroxidation and response to oxidative stress in vitro in liver. The order of liver oxygen consumption and cytochrome oxidase activity among the different species was rat > chick > lizard > frog. The antioxidant defenses supplied by the combined action of glutathione peroxidase and glutathione reductase were not adapted to the respiratory capacities. In particular, there was no correlation either between the activities of two enzymes or between their activities and oxygen consumption. In contrast, the overall antioxidant capacity of the liver appeared to be related to its oxidative capacity, and the malondialdehyde formation, an indirect measure of lipid peroxidation, was inversely related to antioxidant capacity. The response to oxidative stress in vitro indicated that the liver susceptibility to oxidative challenge is higher in ectothermic than in endothermic species. Such higher susceptibility appeared to depend on both lower antioxidant capacity and higher levels of free radical producing species. This finding is apparently in contrast with a higher content of cytochromes in endotherms, which are able to determine both respiratory characteristics and sensitivity to pro-oxidants. However, it could indicate the existence of species-related differences in the tissue content of either preventive antioxidants or hemoproteins able to trap the radicals produced at their active center.
Mechanisms of Ageing and Development, 1993
In order to help clarify whether free radicals are lmphcated or not m the evolution of maximum hfe span (MLSP) of ammals, a comprehenswe study was performed m the hver of various vertebrate species Strongly slgmficant negative correlations against MLSP were found for hepatic catalase, Se-dependent and-mdependent glutathlone peroxldases, and GSH, whereas superoxlde &smutase, glutathlone reductase, ascorbate, uric acid, GSSG/GSH, m vitro peroxldatlon (TBA-RS), and m wvo steady-state H20 2 concentration m the hver &d not correlate w~th MLSP Superoxlde dlsmutase, catalase, glutathlone peroxadase, and GSH results were m agreement w~th those independently reported by other authors, whereas the rest of our data ale reported for the first t~me Potential hmltatlons arising from the use of ammals of &fferent vertebrate Classes were counterbalanced by the poss~bdlty to study animals with very &fferent MLSPs and hfe energy potentmls Furthermore, the results agreed with previous data obtained using only mammals Since hver GSSG/GSH, peroxldataon, and specmlly H~O2 concentrahon were s~mflar in species w~th widely &fferent MLSPs, it is suggested that the decrease m enzymatic H~O2 detoxlfylng capacity of longevous species represents an evolutionary co-adaptation with a smaller m VlVO rate of free ra&cal generation We propose the posslbdlty that maximum longewty was increased during vertebrate evolution by lowering the rate of free ra&cal recychng m the tissues
Mechanisms of ageing and development (1990) 25(4): 389-394
In the lung of Ranaperezi no differences as a function of age have been found for any of the five major antioxidant enzymes, reduced (GSH), oxidized (GSSG) or glutathione ratio (GSSG/GSH), oxygen consumption (X~O2) and for in vivo or in vitro stimulated tissue peroxidation. This frog shows a moderate rate of oxygen consumption and a life span substantially longer than that of rats and mice. Chronic (2.5 months) catalase depletion in the lung did not affect survival or any additional antioxidant enzyme, GSH, GSSG or in vivo and in vitro lung peroxidation in any age group. Only the GSSG/GSH ratio and the ~'O 2 were elevated in catalase depleted old but not young frogs. After comparison of these results with those obtained in other animal species by other authors we suggest the possibility that decreases in antioxidant capacity in old age be restricted to species with high basal metabolic rates. Nevertheless, scavenging of oxygen radicals can not be I00°70 effective in any species. Thus, aging can still he due to the continuous presence of small concentrations of 0 2 radicals in the tissues throughout the life span in animals with either high or low metabolic rates.
Superoxide production, oxidative damage and enzymatic antioxidant defenses in shark skeletal muscle
2010
Pelagic sharks, unlike teleost fish, require constant active swimming to obtain a suitable oxygen (O 2) supply. An increase in O 2 consumption during exercise enhances production of reactive oxygen species (ROS). We hypothesized that shark species that display vigorous exercise, such as Isurus oxyrinchus and Carcharhinus falciformis, have higher ROS production and, in consequence, higher antioxidant enzyme activities in muscle in comparison with species with less active swimming, like Sphyrna zygaena. Superoxide radical (O 2 •−) production, lipid peroxidation levels (TBARS) and the activity of antioxidant enzymes: superoxide dismutase (total, t-SOD; manganese-dependent, Mn-SOD, and copper and zinc-dependent, Cu, Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR), were measured by spectrophotometric assays in skeletal muscle extracts of three shark species (C. falciformis, I. oxyrinchus and S. zygaena). Higher O 2 •− production and GPx and GST activities (p b 0.05) were found in C. falciformis and I. oxyrinchus than in S. zygaena. These results suggest that in antioxidant enzymes (GPx, GST) activity suffices to balance the production of ROS and to maintain lower TBARS levels (p b 0.05) than in C. falciformis or S. zygaena, contributing to the capacity of I. oxyrinchus to maintain high muscular activity.
The International Journal of Biochemistry & Cell Biology, 2005
The effects of hyperoxia on the status of antioxidant defenses and markers of oxidative damage were evaluated in goldfish tissues. The levels of lipid peroxides, thiobarbituric acid reactive substances, carbonyl proteins and the activities of some antioxidant enzymes were measured in brain, liver, kidney and skeletal muscle of goldfish, Carassius auratus L., over a time course of 3-12 h of hyperoxia exposure followed by 12 or 36 h of normoxic recovery. Exposure to high oxygen resulted in an accumulation of protein carbonyls in tissues throughout hyperoxia and recovery whereas lipid peroxides and thiobarbituric acid reactive substances accumulated transiently under short-term hyperoxia stress (3-6 h) but were then strongly reduced. This suggests that hyperoxia stimulated an enhancement of defenses against lipid peroxidation or mechanisms for enhancing the catabolism of peroxidation products. The activities of principal antioxidant enzymes, superoxide dismutase and catalase, were not altered under hyperoxia but catalase increased during normoxic recovery; activities may rise in anticipation of further hyperoxic excursions. In most tissues, the activities of glutathione-utilizing enzymes (glutathione peroxidase, glutathione-S-transferase, glutathione reductase) as well as glucose-6-phosphate dehydrogenase, were not affected under hyperoxia but increased sharply during normoxic recovery. Correlations between some enzyme activities and oxidative stress markers were found, for example, an inverse correlation was seen between levels of thiobarbituric acid reactive substances and glutathione-S-transferase activity in liver and catalase and glucose-6-phosphate dehydrogenase in kidney. The results suggest that liver glutathione-S-transferase plays an important role in detoxifying end products of lipid peroxidation accumulated under hyperoxia stress.
Metabolism of oxidants by blood from different mouse strains
Biochemical Pharmacology, 2006
Blood is regularly subjected to high oxygen tension and is among the first body fluids exposed to exogenous oxidative substances that are ingested, inhaled, or injected. At the same time, it possesses many different protective mechanisms by means of which a delicate balance between oxidizing and reducing species is maintained. Defensive mechanisms include antioxidant enzymes, among which superoxide dismutase and catalase play an important role in detoxifying anion superoxide and hydrogen peroxide. Furthermore, they are provided with lipid phase antioxidants, such as a-tocopherol, and aqueous phase antioxidants such as ascorbic acid, uric acid, and glutathione . Due to its high concentration, reduced glutathione (GSH) is considered the major antioxidant in blood. In addition, because b i o c h e m i c a l p h a r m a c o l o g y 7 1 (
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1994
A comprehensive study was performed on the brains of various vertebrate species showing different fife energy potentials in order to find out if free radicals are important determinants of species-specific maximum life span. Brain superoxide dismutase, catalase, Se-dependent and independent GSH-peroxidases, GSH-reductase, and ascorbic acid showed significant inverse correlations with maximum longevity, whereas GSH, uric acid, GSSGIGSH, in vitro peroxidation (thiobarbituric acid test), and malondialdehyde (measured by HPLC), did not correlate with maximum life span. Superoxide dismutase, catalase, GSH-peroxidase, GSH and ascorbate results agree with those previously reported in various independent works using different animal species. GSSG/GSH, and true malondialdehyde (HPLC) results are reported for the first time in relation to maximum longevity. The results suggest that longevous species simultaneously show low antioxidant concentrations and low levels of in vivo free radical production (a low free radical turnover) in their tissues. The "free radical production hypothesis of aging" is proposed: a decrease in oxygen radical production per unit of 02 consumption near critical DNA targets (mitochondria or nucleus) increases the maximum fife span of extraordinarily iong-fived species like birds, primates, and man. Free radical production near these DNA sites would be a main factor responsible for aging in all the species, in those following Pearl's (Rubner's) metabolic rule as well as in those not following it.
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A meta-analysis of glucocorticoids as modulators of oxidative stress in vertebrates
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2011
Prolonged high secretion of glucocorticoids normally reflects a state of chronic stress, which has been associated with an increase in disease susceptibility and reduction in Darwinian fitness. Here, we hypothesize that an increase in oxidative stress accounts for the detrimental effects of prolonged high secretion of glucocorticoids. We performed a meta-analysis on studies where physiological stress was induced by administration of glucocorticoids to evaluate the magnitude of their effects on oxidative stress. Glucocorticoids have a significant effect on oxidative stress (Pearson r = 0.552), although this effect depends on the duration of treatment, and is larger in long-term experiments. Importantly, there was a significant effect on tissue, with brain and heart being the most and the least susceptible to GC-induced oxidative stress, respectively. Furthermore, effect size was larger (1) in studies using both sexes compared to males only, (2) when corticosterone rather than dexamethasone was administered and (3) in juveniles than in adults. These effects were not confounded by species, biochemical biomarker, or whether wild or laboratory animals were studied. In conclusion, our meta-analysis suggests that GC-induced oxidative stress could be a further mechanism underlying increases in disease susceptibility and decreases in Darwinian fitness observed under chronic stress.
Journal of Comparative Physiology B
Animal life-history traits fall within limited ecological space with animals that have high reproductive rates having short lives, a continuum referred to as a "slow-fast" life-history axis. Animals of the same body mass at the slow end of the life-history continuum are characterized by low annual reproductive output and low mortality rate, such as is found in many tropical birds, whereas at the fast end, rates of reproduction and mortality are high, as in temperate birds. These differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Thus, tropical and temperate birds provide a unique system to examine physiological consequences of life-history trade-offs at opposing ends of the "pace of life" spectrum. We have explored the implications of these trade-offs at several levels of physiological organization including whole-animal, organ systems, ...
How to measure oxidative stress in an ecological context: methodological and statistical issues
Functional Ecology, 2010
1. Reactive oxygen and nitrogen species can damage biomolecules if these lack sufficient antioxidant protection. Maintaining and up-regulating antioxidant defenses and repair of the damaged molecules require resources that could potentially be allocated to other functions, including lifehistory and signal traits. 2. Identifying the physiological mechanisms causing and counteracting oxidative damage may help to understand evolution of oxidative balance systems from molecular to macroevolutionary levels. This review addresses methodological and statistical problems of measuring and interpreting biomarkers of oxidative stress or damage. 3. A major methodological problem is distinguishing between controlled and uncontrolled processes that can lead either to shifts in dynamic balance of redox potential or cause pathological damage. An ultimate solution to this problem requires establishing links between biomarkers of antioxidant defenses and oxidative damage and components of fitness. 4. Biomarkers of redox balance must correspond to strict technical criteria, most importantly to validated measurement technology. Validation criteria include intrinsic qualities such as specificity, sensitivity, assessment of measurement precision, and knowledge of confounding and modifying factors. 5. The complexity of oxidative balance systems requires that assay choice be informed by statistical analyses incorporating context at biochemical, ecological and evolutionary levels. We review proper application of statistical methods, such as principal components analysis and structural equation modelling, that should help to account for these contexts and isolate the variation of interest across multiple biomarkers simultaneously.
PLoS ONE, 2014
Oxidative stress has been implicated as both a physiological cost of reproduction and a driving force on an animal's lifespan. Since increased reproductive effort is generally linked with a reduction in survival, it has been proposed that oxidative stress may influence this relationship. Support for this hypothesis is inconsistent, but this may, in part, be due to the type of tissues that have been analyzed. In Damaraland mole-rats the sole reproducing female in the colony is also the longest lived. Therefore, if oxidative stress does impact the trade-off between reproduction and survival in general, this species may possess some form of enhanced defense. We assessed this relationship by comparing markers of oxidative damage (malondialdehyde, MDA; protein carbonyls, PC) and antioxidants (total antioxidant capacity, TAC; superoxide dismutase, SOD) in various tissues including plasma, erythrocytes, heart, liver, kidney and skeletal muscle between wild-caught reproductive and non-reproductive female Damaraland mole-rats. Reproductive females exhibited significantly lower levels of PC across all tissues, and lower levels of MDA in heart, kidney and liver relative to non-reproductive females. Levels of TAC and SOD did not differ significantly according to reproductive state. The reduction in oxidative damage in breeding females may be attributable to the unusual social structure of this species, as similar relationships have been observed between reproductive and non-reproductive eusocial insects. Citation: Schmidt CM, Blount JD, Bennett NC (2014) Reproduction Is Associated with a Tissue-Dependent Reduction of Oxidative Stress in Eusocial Female Damaraland Mole-Rats (Fukomys damarensis). PLoS ONE 9(7): e103286.
AGE, 2012
The accumulation of oxidative damage to biomolecules, such as DNA, is known to induce alterations in the cell's mechanisms and structure that might lead to the aging process. DNA mismatch repair system (MMR) corrects base mismatches generated during DNA replication that have escaped the proofreading process. In addition, antioxidant enzymes can reduce reactive oxygen species effects in order to protect cells from oxidizing damage. In order to determine the importance of these associated factors during the aging process, in this study, levels of MMR proteins MSH2 and MLH1, as well as microsatellite markers, were compared in liver, lung, and brain of juvenile, adult, and old, both female and male, individuals from two species of wild bats: the short-lived Myotis velifer and the longer lived Desmodus rotundus. Catalase, glutathione peroxidase, and superoxide dismutase were also analyzed to determine if the antioxidant protection correlates negatively with DNA damage. Antioxidant activities were higher in the longer lived D. rotundus than in M. velifer. Furthermore, old M. velifer but not old D. rotundus bats had reduced MMR levels and increased microsatellite instability. Therefore, although our results correlate the reduced MMR efficiency, the deficient antioxidant activity, and the increase in DNA damage with the aging process, this is not always true for all living organisms.
Metabolic adaptations supporting anoxia tolerance in reptiles: Recent advances
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1996
Animal survival during severe hypoxia and/or anoxia is enhanced by a variety of biochemical adaptations including adaptations of fermentative pathways of energy production and, most importantly, the ability to sharply reduce metabolic rate by 5-20 fold and enter a hypometabolic state. The biochemical regulation of metabolic arrest is proving to have common molecular principles that extend across phylogenetic lines and that are conserved in different types of arrested states (not only anaerobiosis but also estivation, hibernation, etc.). Our new studies with anoxia-tolerant vertebrates have identified a variety of regulatory mechanisms involved in both metabolic rate depression and in the aerobic recovery process using as models the freshwater turtle Trachemys scripta elegans and garter snakes Thamnophis sirtalis parietalis. Mechanisms include: 1) post-translational modification of cellular and functional proteins by reversible phosphorylation and changes in protein kinase (PKA, PKC) and/or phosphatase activities to regulate this, 2) reversible enzyme binding associations with subcellular structural elements, 3) differential gene expression and/or mRNA translation producing new mRNA variants and new protein products, 4) changes in protease activity, particularly the multicatalytic proteinase complex, and 5) both constitutive and anoxia-induced modifications to cellular antioxidant systems to deal with oxidative stress during the anoxic-aerobic transition of recovery. COMP mOCHEM PHYSIOL l13B, [23][24][25][26][27][28][29][30][31][32][33][34][35] 1996.
Glutathione disulphide as a marker of reperfusion injury in ischaemic skin flaps
British Journal of Plastic Surgery, 1995
Estimation of the oxidised form of glutathione (GSSG) in an ischaemic/reperfused organ is frequently employed as an indicator of oxidative stress created by the production of oxygen free radicals during the reperfusion period. The time course of oxidative stress and tissue damage in 19 ischaemic/reperfused guinea-pig island skin flaps was evaluated. No-flow ischaemia was induced in the flaps for 6 h in 7 animals, and for 8 h in 9 animals (a further 3 animals served as controls without ischaemia). Arterial and venous blood samples were obtained directly from the flap pedicle at baseline, 10,30, and 60 min following reperfusion. Results suggest that a second focus of oxidative injury, possibly mediated by activated neutrophils, contributes to the overall process of reperfusion injury. Plasma levels of GSSG allow for a more sensitive quantification of oxidant stress within reperfused ischaemic flaps, and may serve as a useful tool in skin flap research.
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How widespread is preparation for oxidative stress in the animal kingdom
It is well known that many anoxia/hypoxia tolerant species when exposed to anoxia/hypoxia respond by increasing the activity/expression of antioxidant enzymes and/or glutathione levels—a phenomenon called " preparation for oxidative stress " (POS). This phenomenon was also observed during freezing exposure, severe dehydration, aerial exposure of water-breathing animals and estivation. However, as far as we know, there is no analysis available of the prevalence of POS among animal species. A major problem is the very definition of POS, since many animal species show both increases and decreases of antioxidants during low oxygen stress and estivation. Therefore, we established three different criteria; from inclusive to restrictive and analyzed how widespread the POS phenomenon is in the animal kingdom. We analyzed all available papers in several databases about the modulation of antioxidant defenses during oxygen deprivation or estivation. Based on the magnitude of change (as % change) during the specific low oxygen stresses or estivation, we classified each species as POS-positive, POS-negative or POS-neutral, considering the three different criteria. The prevalence of POS-positive animals (102 species from 8 phyla) was stress-dependent: in estivation and dehydration it was 91–100%, while in hypoxia it was 37.5–53%, depending on the criteria. In the case of air exposure, anoxia and freezing the proportions of POS-positive species were 54–77%, 64–77% and 75–86%, respectively. Overall, the prevalence of POS was 58 to 68% when all stresses and all species were analyzed together. The results indicate the key importance of POS as a survival strategy of animals exposed to freezing, dehydration and estivation, and, to a lesser extent, to oxygen deprivation itself (i.e. hypoxia and anoxia).
Journal of Experimental Zoology, 1988
Among vertebrates, adult amphibians are known to be especially tolerant to exposure to high environmental oxygen tensions. To clarify the basis for this high 0 2 tolerance, adult Rana ridibunda perezi frogs were acclimated for 15 days to water-air phases with either 149 mm Hg 0 2 (normoxia) or 710 mm Hg 0 2 (hyperoxia). At the end of the acclimation, various morphometric and biochemical paramaters related to oxidative stress were measured in Seven organs and tissues. Hyperoxia acclimation did not change either the total weight of the animals or the total and relative wet weights of the organs studied, except for the brain, which showed weight increases in the hyperoxic group. In vivo tissue peroxidation increased in the kidney; decreased in the skeletal muscle and skin; and did not change in the liver, lung, brain, and heart after hyperoxic exposures. Whereas liver, lung, and skin showed glutathione peroxidase (GSH-P,) activities with both cumene hydroperoxide (cumene-OOH) and H202 as substrates, skeletal muscle only showed HZOZ GSH-P, activity. Hyperoxia acclimation did not change either catalase (CAT) or GSH-P, activities in any organ, except for the liver in which CAT activity was induced by hyperoxia. Thus hyperoxia tolerance in this species does not need the induction of HzO~detoxifying enzymes in the majority of the organs. It is suggested that the high 0 2 tolerance of this amphibian species is related to its comparatively high constitutive GSH-P, activities.
Comparison between the antioxidant status of terrestrial and diving mammals
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2002
Many diving mammals are known for their ability to deal with nitrogen supersaturation and to tolerate apnea for extended periods. They are all characterized by high oxygen-carrying capacity in blood together with high oxygen storage in their muscle mass due to large myoglobin concentrations. The above properties theoretically also imply a high tissue antioxidant defenses (AD) to counteract reactive oxygen species (ROS) generation associated with the rapid transition from apnea to reoxygenation. Different enzymatic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase), and non-enzymatic (levels of glutathione) AD as well as cellular damage (thiobarbituric acid-reactive substances contents, as a measure of lipoperoxidation) were measured in blood samples obtained from anesthetized animals, and also in blood obtained from recently dead diving mammals, and compared to some terrestrial mammals (ns5 in both groups). The results confirmed that diving mammals have, in general, higher antioxidant status compared to non-diving mammals. Apparently, to avoid exposure of tissues to changing high oxygen levels, and therefore to avoid an oxidative stress condition related to antioxidant consumption and increased ROS generation, diving mammals possess constitutive high levels of antioxidants in tissues. These data are in agreement with short-term AD adaptations related to torpor and to animals that experience large daily changes in oxygen consumption. These data are similar to the long-term adaptations of animals that undergo hibernation, estivation, freezing-thawing and dehydration-rehydration processes. In summary, animals that routinely face high changes in oxygen availability andyor consumption seem to show a general strategy to prevent oxidative damage by having either appropiate high constitutive AD andyor the ability to undergo arrested states, where depressed metabolic rates minimize the oxidative challenge. ᮊ
Redox physiology in animal function: The struggle of living in an oxidant environment
2010
A strong focus of ecological research for several decades has been to understand the factors underlying the variation in animal life-histories. In recent times, ecological studies have begun to show that oxidative stress may represent another important modulator of competitive trade-offs among fitness traits or of positively integrated patterns of traits. Therefore, incorporating mechanisms underlying oxidative physiology into evolutionary ecology has the potential to help understand variation in life-history strategies. In this review, I provide a general overview of oxidative stress physiology, and subsequently focus on topics that have been neglected in previous ecological reviews on oxidative stress. Specifically, I introduce and discuss the adaptations that animals have evolved to cope with oxidative stress; the environmental stressors that can generate changes in oxidative balance; the role of reactive species in transduction of environmental stimuli and cell signaling; and the range of hormetic responses to oxidative stress [Current Zoology 56 : [687][688][689][690][691][692][693][694][695][696][697][698][699][700][701][702] 2010].
Journal of Comparative Physiology B, 1994
It has been proposed that antioxidants can be longevity determinants in animals. However, no comprehensive study has been conducted to try to relate free radicals with maximum life span. This study compares the lung tissue of various vertebrate species -amphibia, mammals and birds -showing very different and well known maximum life spans and life energy potentials. The lung antioxidant enzymes superoxide dismutase, catalase, Se-dependent and non-Se-dependent glutathione peroxidases, and glutathione reductase showed significantly negative correlations with maximum life span. The same was observed for the lung antioxidants, reduced glutathione and ascorbate. It is concluded that a generalized decrease in tissue antioxidant capacity is a characteristic of longevous species. It is suggested that a low rate of free radical recycling (free-radical generation and scavenging) can be an important factor involved in the evolution of high maximum animal longevities. A low free-radical production could be responsible for a low rate of damage at critical sites such as mitochondrial DNA.
The International Journal of Biochemistry & Cell Biology, 2005
The effects of hypoxia exposure and subsequent normoxic recovery on the levels of lipid peroxides (LOOH), thiobarbituric acid reactive substances (TBARS), carbonylproteins, total glutathione levels, and the activities of six antioxidant enzymes were measured in brain, liver, kidney and skeletal muscle of the common carp Cyprinus carpio. Hypoxia exposure (25% of normal oxygen level) for 5 h generally decreased the levels of oxidative damage products, but in liver TBARS content were elevated. Hypoxia stimulated increases in the activities of catalase (by 1.7-fold) and glutathione peroxidase (GPx) (by 1.3-fold) in brain supporting the idea that anticipatory preparation takes place in order to deal with the oxidative stress that will occur during reoxygenation. In liver, only GPx activity was reduced under hypoxia and reoxygenation while other enzymes were unaffected. Kidney showed decreased activity of GPx under aerobic recovery but superoxide dismutase (SOD) and catalase responded with sharp increases in activities. Skeletal muscle showed minor changes with a reduction in GPx activity under hypoxia exposure and an increase in SOD activity under recovery. Responses by antioxidant defenses in carp organs appear to include preparatory increases during hypoxia by some antioxidant enzymes in brain but a more direct response to oxidative insult during recovery appears to trigger enzyme responses in kidney and skeletal muscle.
Journal of Neuroscience Research, 1990
The five major antioxidant enzymes, glutathione, and in vivo or in vitro stimulated (Fe++-ascorbate) peroxidation were similar in old and young Rana perezi frogs. Long-term (2.5 months) treatment with aminotriazole strongly decreased cerebral catalase (CAT) activity and increased in vivo but not in vitro peroxidation in the brain. This suggests that the increase in endogenous brain peroxidation after CAT inhibition is due to an increased free-radical attack on cerebral membranes, and not to a possible increase in their sensitivity to peroxidative damage. The increase of in vivo peroxidation is especially remarkable taking into account the low levels of CAT present in the vertebrate brain. On the other hand, these changes were not accompanied by any effect on the survival of the animals. Comparison of these results with those obtained in other species suggests the possibility that 0,-free radicals be of minor importance in relation to brain aging in animals with low rates of oxygen consumption.
Oxidative stress and antioxidant enzymes in liver and white muscle of Nile
Oxidative stress and antioxidant enzyme activities in liver and white muscle of Nile tilapia (Oreochromis niloticus) juveniles (10 ± 1.2 g) in chronic exposure to sublethal total ammonia nitrogen (TAN) were studied. The fish were exposed to the TAN concentrations, 5 mg L −1 (low) or 10 mg L −1 (high) for consecutive 70 days at 26 ± 0.5 • C temperature. At the end of experimental period, lipid peroxidation and protein carbonylation levels and the activities of xanthine oxidase (XO), aldehyde oxidase (AO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), ␥-glutamyl cysteinyl synthetase (␥-GCS), and ␥-glutamyl transpeptidase (␥-GT) in liver and white muscle were assayed. The levels of oxidative stress biomarkers and the activities of the enzymes assayed were significantly increased in liver and white muscle of fish exposed to both low and high TAN levels. The changes in these parameters were intensified at high TAN level. The significance of these alterations in enzyme activities is discussed.
Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology, 1995
A comparison of the erythrocyte (RBC) antioxidant metabolites and enzymes in nine marsupial and two monotreme species was carried out. Reduced glutathione (GSH) concentrations were comparable with those reported for other marsupial and eutherian species. An important finding was that the erythrocytes of the southern hairy nosed wombat regenerated GSH faster than the erythrocytes from its close relative, the common wombat. The activities of glutathione-S-transferase, NADH-methaemoglobin reductase, superoxide dismutase, and glutathione peroxidase (GSH-Px), showed similar levels and extents of variation as those observed in other marsupial and eutherian species. Catalase activities in the marsupials were lower than those measured in the two monotreme species and much lower than those reported in eutherian species. A negative correlation, significant at P < 0.05, was observed between GSH-Px and catalase activities in the RBC of the marsupials. Since both these enzymes "detoxify" H 2 0 2 , there appears to be a reciprocal relationship between the activities of these enzymes in marsupial RBC.
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