Cloning and mRNA expression of antioxidant enzymes in the Pacific oyster, Crassostrea gigas in response to cadmium exposure

Cadmium (Cd) is one of the most toxic heavy metal pollutants in the aquatic environment and can induce the formation of reactive oxygen species (ROS) that cause oxidative stress. In present study, we cloned catalase (CAT) and glutathione peroxidase (GPX) cDNA, and investigated its time- and dose-related effects of three Cd concentrations (0.01, 0.05 or 0.1 ppm) on mRNA levels of antioxidant enzymes (superoxide dismutase (SOD), CAT, GPX) in the gill and changes enzyme levels in the hemolymph of the Pacific oyster, Crassostrea gigas. The cDNA indentified encoded proteins of 516 and 244 amino acids corresponding to CAT and GPX, respectively. BLAST analysis from other species indicated that the residues essential to the enzymatic function of CAT and GPX proteins of C. gigas are highly conserved. Cd treatment significantly increased antioxidant enzyme mRNA expression in the gill in a time- and dose-dependent manner. The mRNA expression at 0.1 ppm Cd concentration increased up to 3 days (CAT, GPX) or 7 days (SOD) and then decreased by 7 days (CAT, GPX) or 11 days (SOD). Aspartate aminotransferase, alanine amintransferase and hydrogen peroxide (H(2)O(2)) concentrations levels increased significantly with exposure to 0.05 or 0.1 ppm Cd for 7 days. These results suggest that antioxidant enzymes play important roles in the physiological changes related to metabolism and cell protection that occur in Pacific oysters exposed to Cd.     

Antioxidant defence enzyme activities in hepatopancreas, gills and muscle of Spiny cheek crayfish (Orconectes limosus) from the River Danube

The aim of our study was to determine the activity of antioxidant defence (AD) enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and the phase II biotransformation enzyme glutathione-S-transferase (GST) in the hepatopancreas, the gills and muscle of Spiny cheek crayfish (Orconectes limosus) from the River Danube and to compare tissue specificities of investigated enzymes. Our results indicated that both specific and total SOD activities in the hepatopancreas were lower compared to the gills and muscle. Total SOD activity in the gills was lower with respect to that in muscle. CAT and GSH-Px (both specific and total) activities were higher in the hepatopancreas compared to those in the gills and muscle. In the gills the specific and total GR activities were higher than in the hepatopancreas and muscle. The specific and total GST activities were higher in the hepatopancreas compared with the gills and muscle. Our study represents the first comprehensive report of AD enzymes in tissues of O. limosus caught in the River Danube. The noted tissue distributions of the investigated AD enzyme activities most likely reflected different metabolic activities and different responses to environmental conditions in the examined tissues.     

镉对长江华溪蟹肝胰腺抗氧化酶活力的影响

重金属对环境的污染已成为全球面临的首要问题之一,其中镉(Cd2 )是一种广泛存在的毒性污染物,能通过消化道和呼吸道进入生物体,对机体造成损伤(Zyadah and Abdel-Baky,2000)。研究表明,Cd2 可以通过Ca2 通道穿过细胞膜进入机体(Roesijadi and Robinson,1994),诱导产生大量自由基和活性氧(ROS),从而形成氧胁迫(Toppi andGabbrielli,1994;Hegedus et al.,2001)。ROS可以与体内脂质、蛋白质和核酸反应,导致脂质过氧化、细胞膜损伤并且影响多种酶的活力,对生物体造成威胁。由于在水生生态系统中生物富集污染物的作用明显,故相对于陆地生…     

Effect of vitamin E and selenium on antioxidant enzymes in brain,kidney and liver of cigarette smoke-exposed mice

The present study was conducted to evaluate the protective effects of vitamin E and selenium (Se) application on alteration of antioxidant enzyme activities against cigarette smoking induced oxidative damage in brains, kidneys and liver of mice. Male mice (balb/c) were exposed to cigarette smoke and treated with Se and/or vitamin E. Glutathione transferase (GST), glutathione peroxidase (GPX), glutathione reductase (GRX), superoxide dismutase (SOD) and catalase (CAT) enzyme activities in mice brain, kidney and liver were measured spectrophotometrically. GST, GPX, GRX, SOD and CAT enzyme activities in the brains of smoke-exposed mice were found lower than the enzymes activities of control mice and Se-and vitamin E-treated mice at the end of the three and five months. Opposite to brain, enzyme activities in kidneys and livers of smoke-exposed mice were found higher than the enzymes activities of control mice and Se-and vitamin E-treated mice at the end of the three and five months. Activities of GST, GPX, GRX SOD and CAT in the livers, kidneys and brains of smoke-exposed mice were found statistically different (p < 0.01) compared to control mice and Se-and vitamin E-treated mice. Combined application of vitamin E and Se had an additive protective effect against changing enzymes activities in smoke-exposed mice livers, kidneys and brains at the end of the both application periods. These results suggest that cigarette smoke exposure enhances the oxidative stress, thereby disturbing the tissue antioxidant defense system and combined application of vitamin E and Se protects the brain, kidney and liver from oxidative damage through their antioxidant potential.     

Comparison between the effects of normoxia and hypoxia on antioxidant enzymes and glutathione redox state in ex vivo culture of CD34(+) cells

Hypoxia maintained biological characteristics of CD34(+) cells through keeping lower intracellular reactive oxygen specials (ROS) levels. The effects of normoxia and hypoxia on antioxidant enzymes and glutathione redox state were compared in this study. Hypoxia decreased the mRNA expression of both catalase (CAT) and glutathione peroxidase (GPX), but not affected mRNAs expression of superoxide dismutase (SOD). While the cellular GPX activities under hypoxia were apparently less than those under normoxia, neither SOD activities nor CAT activities were affected by hypoxia. The analysis of glutathione redox status and ROS products showed the lower oxidized glutathione (GSSG) levels, the higher reduced glutathione (GSH) levels, the higher GSH/GSSG ratios, and the less O(2)- and H(2)O(2) generation under hypoxia (versus normoxia). Meanwhile more primary CD34(+)CD38(-) cells were obtained when cultivation was performed under hypoxia or with N-acetyl cysteine (the precursor of GSH) under normoxia. These results demonstrated the different responses of anti-oxidative mechanism between normoxia and hypoxia. Additionally, the present study suggested that the GSH-GPX antioxidant system played an important role in HSPCs preservation by reducing peroxidation.     

Physiological (antioxidant) responses of estuarine fishes to variability in dissolved oxygen

Cycles of dissolved oxygen (DO) in estuaries can range from anoxia to various levels of supersaturation (200–300%) over short time periods. Aerobic metabolism causes formation of damaging reactive oxygen species (ROS), a process exacerbated by high or low DO. Fish can generate physiological defenses (e.g. antioxidant enzymes) against ROS, however, there are little data tying this to environmental conditions. We investigated physiological defenses generated by estuarine fishes in response to high DO and various DO cycles. We hypothesized that chemical defenses and/or oxidative damage are related to patterns of DO supersaturation. Specific activities of antioxidants in fish tissues should be positively correlated with increasing levels of DO, if high DO levels are physiologically stressful. We caged common benthic fishes (longjaw mudsucker, Gillichthysmirabilis, and staghorn sculpin, Leptocottusarmatus, in CA and spot, Leiostomusxanthurus and pinfish, Lagodonrhomboides, in NC) during summer 1998 in two estuarine sites in southern North Carolina and two in central California. At each site a water quality meter measured bottom DO, salinity, temperature, depth, pH and turbidity at 30 min intervals throughout the study. These sites exhibited a wide variety of dissolved oxygen patterns. After 2 weeks in the cages, fish gills and livers were analyzed for antioxidant enzymes (glutathione peroxidase, catalase and superoxide dismutase) and the metabolite glutathione. All fish exhibited antioxidant enzyme activity. There was a significant site-dependent effect on all enzyme activities at the NC sites, with the most activity at the site with the highest DO cycling and the most DO supersaturation. There was a trend towards higher enzyme activities under high DO levels at the CA sites.     

2-Benzoxazolinone (BOA) induced oxidative stress, lipid peroxidation and changes in some antioxidant enzyme activities in mung bean (Phaseolus aureus)

2-Benzoxazolinone (BOA), a well-known allelochemical with strong phytotoxicity, is a potential herbicidal candidate. The aim of the present study was to determine whether phytotoxicity of BOA is due to induction of oxidative stress caused by generation of reactive oxygen species (ROS) and the changes in levels of antioxidant enzymes induced in response to BOA. Effect of BOA was studied on electrolyte leakage, lipid peroxidation (LP), hydrogen peroxide (H(2)O(2)) generation, proline (PRO) accumulation, and activities of antioxidant enzymes-superoxide dismutase (SOD, 1.15.1.1), ascorbate peroxidase (APX, 1.11.1.11), guaiacol peroxidase (GPX, 1.11.1.7), catalase (CAT, 1.11.1.6) and glutathione reductase (GR, 1.6.4.2) in Phaseolus aureus (mung bean). BOA significantly enhanced malondialdehyde (MDA) content, a product of LP, in both leaves and roots of mung bean. The amount of H(2)O(2), a product of oxidative stress, and endogenous PRO increased many-fold in response to BOA. Accumulation of PRO, MDA and H(2)O(2) indicates the cellular damage in the target tissue caused by ROS generated by BOA. In response to BOA, there was a significant increase in the activities of scavenging enzymes SOD, APX, GPX, CAT, and GR in root and leaf tissue of mung bean. At 5 mM BOA, GR activity in roots showed a nearly 22-fold increase over that in control. The present study concludes that BOA induces oxidative stress in mung bean through generation of ROS and upregulation of activities of various scavenging enzymes.     

Time course variations of antioxidant enzyme activities and histopathology of gilthead seabream gills exposed to malathion

In a widely distributed and commercially important fish, gilthead seabream Sparus aurata L., we have studied sublethal effects of malathion in order to identify early warning bioindicators of exposure before irreversible damage occurs. To achieve this goal, groups of 10 juvenile specimens were exposed for 24, 48, 72 and 96 h to a sublethal concentration of malathion (0.4 mg/l). Another group was used as control. The activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) and histopathological features from exposed gills were assessed. It should also be mentioned that no mortality was observed during the whole experience. The activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) were altered significantly from 24 h onward (p<0.05). It is of interest to note that catalase activity was decreased after exposure instead of increasing as other antioxidant enzymes assessed. On the other hand, histopathological alterations of the gills were observed as early as at 48 h-exposure, but the most severe damage occurred at 96 h exposure. The evidence presented here, together with other data from the literature, unequivocally established oxidative-stress-inducing effects of malathion in gilthead seabream Sparus aurata. It is also concluded antioxidants employed (SOD, CAT and GPX) changed significantly a long time before histopathological alterations of gills became evident. Consequently, these antioxidant enzymes may be highly recommended as early-warning bioindicators of environmental pollution by malathion in the areas where it is proposed to be used in pest control activities.     

Biochemical markers of oxidative stress in Perna viridis exposed to mercury and temperature

Oxidative damage and antioxidant properties have been studied in Perna viridis subjected to short-term exposure to Hg along with temperature (72h) and long-term temperature exposures (14 days) as pollution biomarkers. The elevated thiobarbituric acid reactive substances (TBA-RS) levels observed in gills and digestive gland under exposure to Hg, individually and combined with temperature, as also long-term temperature stress have been assigned to the oxidative damage resulting in lipid peroxidation (LPX). Increased activities of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) both in gills and digestive glands under long-term exposures to temperatures are more prominent to heat rather than cold stress suggesting activation of physiological mechanism to scavenge the ROS produced during heat stress. Also decreased values of reduced glutathione (GSH) on long exposures to temperature stress indicate utilisation of this antioxidant, either to scavenge oxiradicals or act in combination with other enzymes, was more than its production capacity under heat stress. The results suggest that temperature variation does alter the active oxygen metabolism by modulating antioxidant enzyme activities, which can be used as biomarker to detect sublethal effects of pollution.     

Antioxidant response of the bivalve Pinna nobilis colonised by invasive red macroalgae Lophocladia lallemandii

Invasive species represent a risk to natural ecosystems and a biodiversity hazard. The present work aims to determine the antioxidant enzyme response – superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), the phase II detoxifying enzyme – glutathione S-transferase (GST) – and markers of oxidative damage – thioredoxin reductase (TR) and malondialdehyde (MDA) – in gills and digestive gland of Pinna nobilis and to study the antioxidant response effects in the bivalve colonised by the invasive macroalgae Lophocladia lallemandii. Colonised specimens were collected in a control area without L. lallemandii and another area completely colonised by L. lallemandii. All enzyme activities were found to be present in gills and digestive gland, with some tissue differences. CAT and SOD activities were higher in gills than digestive gland, whereas GST activity and MDA levels were higher in digestive gland. The presence of L. lallemandii induced a significant increase in the activities of antioxidant enzymes in both gills and digestive gland, except for CAT activity in gills. GST and TR activities were also increased in both tissues, as well as the MDA concentration. We can conclude that the presence of L. lallemandii colonising P. nobilis induces a biological stress and oxidative damage to the fan mussel.     

Superoxide dismutase, catalase and glutathione peroxidase activities in the brain of streptozotocin induced diabetic rats

Brain antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) levels were studied in the brains of early diabetic (72 hr) and long term diabetic (one month) rats. Diabetes was induced by injecting streptozotocin (50 mg/kg, i.p.) in citrate buffer. One group of diabetic rats was treated with insulin (1U/day/animal). The results indicate that early diabetic rats exhibit increased SOD and CAT activities with no alteration in the GPX activity. On the contrary, increased CAT decreased GPX activities with no alteration in the SOD activity, was noted in the long-term Diabetic rats. Insulin treatment reversed these alterations in both the groups. It can be concluded that, in diabetic condition antioxidant enzyme levels are elevated and insulin treatment attenuated these changes. Hence, diabetes mellitus, if left untreated, may initiate degenerative processes and other CNS complications due to accumulation of oxidative free radicals.     

Gene expression evaluation of antioxidant enzymes in patients with hepatocellular carcinoma: RT-qPCR and bioinformatic analyses

Any condition leading to chronic liver disease is a potential oncogenic agent for hepatocellular carcinoma (HCC). Alterations in the expression of antioxidant enzymes could alter the redox balance. Our aim was to evaluate the expression of the genes GPX1, GPX4, SEP15, SELENOP, SOD1, SOD2, GSR, CAT, and NFE2L2 in patients with HCC. Differential gene expression analysis was performed using RNA-Seq data from the TCGA and GTEx databases, and RT-qPCR data from HCC patient samples. Bioinformatic analysis revealed significant differential expression in most genes. GPX4 expression was significantly increased (p=0.02), while SOD2 expression was significantly decreased (p=0.04) in experimental data. In TCGA samples, alpha-fetoprotein levels (mg/dL) were negatively correlated with the expression of SEP15 (p<0.001), SELENOP (p<0.001), SOD1 (p<0.001), SOD2 (p<0.001), CAT (p<0.001), and NFE2L2 (p=0.004). Alpha-fetoprotein levels were positively correlated with the expression of GPX4 (p=0.02) and SELENOP (p=0.01) in the experimental data. Low expression of GPX1 (p=0.006), GPX4 (p=0.01), SELENOP (p=0.006), SOD1 (p=0.007), CAT (p<0.001), and NFE2L2 (p<0.001), and higher levels of GSR, were associated with low overall survival at 12 months. These results suggest a significant role for these antioxidant enzymes in HCC pathogenesis and severity.     

alpha-Pinene inhibits growth and induces oxidative stress in roots

BACKGROUND AND AIMS: Determining the mode of action of allelochemicals is one of the challenging aspects in allelopathic studies. Recently, allelochemicals have been proposed to cause oxidative stress in target tissue and induce an antioxidant mechanism. alpha-Pinene, one of the common monoterpenoids emitted from several aromatic plants including forest trees, is known for its growth-inhibitory activity. However, its mechanism of action remains unexplored. The aim of the present study was to determine the inhibitory effect of alpha-pinene on root growth and generation of reactive oxygen species, as indicators of oxidative stress and changes in activities of antioxidant enzymes. METHODS: Effects of alpha-pinene on early root growth were studied in five test species, Cassia occidentalis, Amaranthus viridis, Triticum aestivum, Pisum sativum and Cicer arietinum. Electrolyte leakage, lipid peroxidation, hydrogen peroxide generation, proline accumulation, and activities of the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT) and glutathione reductase (GR) were studied in roots of C. occidentalis. KEY RESULTS: alpha-Pinene inhibited the radicle growth of all the test species. Exposure of C. occidentalis roots to alpha-pinene enhanced solute leakage, and increased levels of malondialdehyde, proline and hydrogen peroxide, indicating lipid peroxidation and induction of oxidative stress. Activities of the antioxidant enzymes SOD, CAT, GPX, APX and GR were significantly elevated, thereby indicating the enhanced generation of reactive oxygen species (ROS) upon alpha-pinene exposure. Increased levels of scavenging enzymes indicates their induction as a secondary defence mechanism in response to alpha-pinene. CONCLUSIONS: It is concluded that alpha-pinene inhibits early root growth and causes oxidative damage in root tissue through enhanced generation of ROS, as indicated by increased lipid peroxidation, disruption of membrane integrity and elevated antioxidant enzyme levels.     

镉对尖紫蛤抗氧化酶活性及脂质过氧化的影响

为阐明镉(Cd2+)对尖紫蛤消化盲囊和鳃抗氧化酶的毒性影响程度,研究了不同浓度的Cd2+(0.005、0.05、0.5 mg/L)在不同暴露时间(24h、72h、120h)对尖紫蛤鳃和消化盲囊中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-PX)的活性以及丙二醛(MDA)含量的影响。结果表明,在Cd2+浓度为0.005 mg/L时,在整个实验期间Cd2+对消化盲囊和鳃内的SOD、CAT、GSH-PX活性并无显著影响。在Cd2+浓度为0.05 mg/L和0.5 mg/L时,SOD、CAT、GSH-PX在鳃和消化盲囊中的活性都呈现出明显的时间剂量依赖关系。在0.05 mg/L暴露时,鳃和消化盲囊中的SOD、CAT和GSH-PX的活性随时间逐渐增强,在72h时达到最大值,但在120h时略有降低。在0.5 mg/L暴露时,消化盲囊中SOD、CAT及鳃中CAT活性在24h时上升达到最大值,但鳃中SOD直到72h才达到最大值,并均在120h下降到最低,其中消化盲囊中SOD和CAT活性在120h低于对照组,这可能与消化盲囊对Cd2+的敏感性高于鳃有关。在0.5 mg/L暴露的鳃中,GSH-PX在24h、72h活性并不上升,在120h甚至低于正常水平,0.5 mg/L暴露的消化盲囊中,24h时迅速增高,然后逐渐下降到正常值。这可能与Cd2+结合了GSH-PX的活性中心,降低了GSH-PX的活性有关。与3种酶活性随着时间延长和剂量的增加,酶活性会降低的变化趋势不同,鳃和消化盲囊中的MDA的含量随时间延长和剂量的增加而增加,并不出现下降,这表明尖紫蛤鳃和消化盲囊中的MDA含量可以灵敏的反映机体内的氧化损伤程度,但不能敏感的反映水体中Cd2+的污染情况。     

渗透胁迫对黑麦幼苗活性氧和抗氧化酶活性的影响

用20%聚乙二醇(PEG 6000)研究了渗透胁迫对黑麦(Secale cereale L.)幼苗活性氧(reactive oxygen species, ROS)和主要抗氧化酶—— 超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)、抗坏血酸过氧化物酶(ascorbate peroxidase, APX)和谷胱甘肽还原酶(glutathione reductase, GR)活性的影响。结果表明, 与对照相比, PEG处理明显提高了叶子和根中丙二醛(malondialdehyde, MDA)的含量、ROS的水平和以上4种抗氧化酶的活性。渗透胁迫下,叶子和根中MDA和ROS水平变化的规律基本相似, 但抗氧化酶活性在2种器官中表现不完全相同, 叶子中CAT的活性在对照和处理中无显著差异, 但在根中差异明显, 表明叶子中SOD、APX和GR在植物应答渗透胁迫中起重要作用, 而根中这4种抗氧化酶都参与植物对胁迫的反应。GR活性随PEG处理变化幅度显著高于其它抗氧化酶, 表明GR在黑麦应答渗透胁迫中所起作用可能强于其它抗氧化酶。     

Skeletal muscle oxidative capacity, antioxidant enzymes, and exercise training

The purposes of this study were to determine whether exercise training induces increases in skeletal muscle antioxidant enzymes and to further characterize the relationship between oxidative capacity and antioxidant enzyme levels in skeletal muscle. Male Sprague-Dawley rats were exercise trained (ET) on a treadmill 2 h/day at 32 m/min (8% incline) 5 days/wk or were cage confined (sedentary control, S) for 12 wk. In both S and ET rats, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) activities were directly correlated with the percentages of oxidative fibers in the six skeletal muscle samples studied. Muscles of ET rats had increased oxidative capacity and increased GPX activity compared with the same muscles of S rats. However, SOD activities were not different between ET and S rats, but CAT activities were lower in skeletal muscles of ET rats than in S rats. Exposure to 60 min of ischemia and 60 min of reperfusion (I/R) resulted in decreased GPX and increased CAT activities but had little or no effect on SOD activities in muscles from both S and ET rats. The I/R-induced increase in CAT activity was greater in muscles of ET than in muscles of S rats. Xanthine oxidase (XO), xanthine dehydrogenase (XD), and XO + XD activities after I/R were not related to muscle oxidative capacity and were similar in muscles of ET and S rats. It is concluded that although antioxidant enzyme activities are related to skeletal muscle oxidative capacity, the effects of exercise training on antioxidant enzymes in skeletal muscle cannot be predicted by measured changes in oxidative capacity.     

Increases of Catalase and Glutathione Peroxidase Expressions by Lacosamide Pretreatment Contributes to Neuroprotection Against Experimentally Induced Transient Cerebral Ischemia

Lacosamide is a new antiepileptic drug which is widely used to treat partial-onset seizures. In this study, we examined the neuroprotective effect of lacosamide against transient ischemic damage and expressions of antioxidant enzymes such as Zn-superoxide dismutase (SOD1), Mn-superoxide dismutase (SOD2), catalase (CAT) and glutathione peroxidase (GPX) in the hippocampal cornu ammonis 1 (CA1) region following 5 min of transient global cerebral ischemia in gerbils. We found that pre-treatment with 25 mg/kg lacosamide protected CA1 pyramidal neurons from transient global cerebral ischemic insult using hematoxylin–eosin staining and neuronal nuclear antigen immunohistochemistry. Transient ischemia dramatically changed expressions of SOD1, SOD2 and GPX, not CAT, in the CA1 pyramidal neurons. Lacosamide pre-treatment increased expressions of CAT and GPX, not SOD1 and 2, in the CA1 pyramidal neurons compared with controls, and their expressions induced by lacosamide pre-treatment were maintained after transient cerebral ischemia. In brief, pre-treatment with lacosamide protected hippocampal CA1 pyramidal neurons from ischemic damage induced by transient global cerebral ischemia, and the lacosamide-mediated neuroprotection may be closely related to increases of CAT and GPX expressions by lacosamide pre-treatment.     

Met-enkephalin modulation of age-related changes in red cell antioxidant status

Opioid peptides have been recognized as modulators of reactive oxygen species (ROS) in mouse macrophages and human neutrophils. Since the effect cannot be ascribed to its direct scavenger properties, in this study, we tested the hypothesis that methionine-enkephalin (MENK) modulates ROS by alteration of antioxidant enzyme activity (AOE). For this purpose superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) are measured in red blood cells of 1, 4, 10, and 18-month-old CBA mice of both sexes injected with 10 mg/kg MENK. The results indicate that MENK-affected antioxidant enzyme activity of red blood cells is age- but not sex-related. The most abundant effects were observed at the reproductive stage. Increased sensitivity to oxidative stress by opioid peptides was in both sexes mainly due to increased SOD activity followed by GPX decrease. Thus, the damage ascribed to opioid peptides might be, at least partly, ascribed to deleterious effects of accumulated hydrogen peroxide (H2O2).     

Altered levels of primary antioxidant enzymes in progeria skin fibroblasts

Free radicals are involved in the aging process. In this study, the profile of primary antioxidant enzymes that scavenge reactive oxygen species (ROS) was examined for the first time in human skin fibroblasts from progeria, a premature aging disease. Altered levels of antioxidant enzymes were found in progeria cells. Basal levels of MnSOD were decreased in progeria cells as well as a blunted induction in response to chronic stress. This change may contribute to the accelerated aging process in progeria cells. In contrast, the levels of CuZnSOD showed no progeria-related change. Two H2O2 removing enzymes demonstrated a significant reduction in progeria cells: only 50% of normal CAT activity and 30% of normal GPX activity can be detected in progeria cells. This diminished H2O2 removing capacity in progeria cells may lead to an imbalance of intracellular ROS and therefore may play an important role in the development of progeria.     

Different levels of hyperoxia reversibly induce catalase activity in amphibian tadpoles

Studies about the proposed antioxidant physiological role of the catalase (CAT) enzyme in relation to different environmental oxygen tensions are reported for the first time in amphibian larvae of Discoglossus pictus and Rana ridibunda perezi during their development. The CAT levels of whole tadpoles increased constantly in both species during the larval period, reaching a maximum during the metamorphic climax. All through development, CAT activity levels were always greater in D. pictus than in R. ridibunda perezi. This correlates well with the already reported higher SOD activity and hyperoxia resistance of the D. pictus species when compared to R. ridibunda perezi. Long-term acclimation to different levels of hyperoxia (40, 60, and 100% O2) showed dose-related increases in the CAT activity of D. pictus tadpoles. These increases did not take place when the animals were subjected to acute hyperoxia (24 h). The increase in CAT activity observed after 15 days of acclimation to acute hyperoxia (710 mm Hg: 100% O2) was reversed after 15 additional days of postacclimation to normal air (149 mm Hg O2). When recently metamorphosed frogs were acclimated to acute hyperoxia, significant increases in CAT activity were observed after 15 days, but not after 7 days. The results are interpreted as supporting a protective role for the CAT enzyme in amphibian larvae and froglets against oxygen toxicity.