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.
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.
Antioxidant parameters and ageing in some animal species
Comparative Haematology International, 1996
Connection between ageing and some tissue antioxidant parameters have been studied in four experiments on different animal species. Prenatal studies on the developing chick embryos showed discrepancies between the lipid-rich liver and brain antioxidant defence. In the liver, high levels of reduced glutathione (GSH), vitamins A and E and high activities of the antioxidant enzymes glutathione peroxidase (GPX) and superoxide dismutase (SOD) were found whereas brain expressed a high vitamin C concentration. In newborn healthy calves during the first two days of life, atmospheric oxygen tension did not cause either increased lipid peroxidation as reflected in a high malondialdehyde (MDA) level or any changes in GSH, GPX, SOD and catalase (CAT) activities in red blood cells (RBC). Plasma vitamin E and carotene concentrations also did not change. In growing healthy calves during two months after birth increasing MDA, decreasing GSH, GPX and CAT are leading features, whereas plasma vitamin E and carotene concentrations significantly increased. In young (1-year-old) and old (9-year-old) dogs RBC results showed significant differences with the highest MDA and lowest GSH levels in the old males. Activity of GPX and SOD was higher in old dogs than in the young ones, especially in the females.
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