Aminotriazole effects on lung and heart H2O2 detoxifying enzymes and TBA-RS at two pO2

Impairment of antioxidant mechanisms in Japanese Medaka (Oryzias latipes) by acute exposure to aluminum

Increasing aluminum (Al) concentrations in aquatic habitats as a result of anthropogenic acidification and industrialization is a global issue. Moreover, in extensive areas of the humid tropics and subtropics, high Al concentrations in freshwater are observed because of both naturally low pH and high Al concentrations in soil. Al increases production of reactive oxygen species and enhances oxidative damage in mammals. However, no studies have examined the effect of environmentally relevant concentrations of Al at low pH on oxidative stress in fish. This study assessed Al-induced effects on enzymatic and non-enzymatic antioxidants, lipid peroxidation, and on expression of oxidative stress-related genes at low pH using Japanese Medaka (Oryzias latipes). Larval fish were exposed to dissolved Al concentrations of 0, 1.7, 6.2 and 16.7μgL^-1 for 4days at pH5.3 in soft water. Al caused a significant reduction in activity of glutathione peroxidase at 6.2 and 16.7μgL^-1, and of glutathione reductase at 16.7μgL^-1 in whole body homogenates. No changes were observed in the expression of the glutathione peroxidase gene, and expression levels of the glutathione reductase gene were too low to be quantitated. Even though there was an overall decrease in the activity of catalase and in the concentration of glutathione, differences were not significant compared to the control. Changes in lipid peroxidation were not found. This study showed that exposure to environmentally relevant concentrations of Al at low pH impairs antioxidant defense mechanisms of Medaka.

Effects of prolonged exposure to low pH on enzymatic and non-enzymatic antioxidants in Japanese Medaka (Oryzias latipes)

Acidification in aquatic ecosystems is a major concern worldwide. In freshwater, although there are several publications reporting acute toxicity and adverse effects due to low pH, little is known about adverse effects on antioxidant mechanisms in fish after prolonged exposure. This study aimed to investigate how antioxidants are affected by raising larval Japanese Medaka (Oryzias latipes) in soft water at pH5.5, 6.0, and 6.5. After 18days of exposure, glutathione concentration and glutathione peroxidase activity in whole body homogenates increased as pH decreased, without changes in lipid peroxidation measured as thiobarbituric acid reactive substances. This study showed that prolonged exposure to low pH increased reactive oxygen species production and that fish cope with it by increasing levels of enzymatic and non-enzymatic antioxidants.

Physiological studies on the effect of copper nicotinate (Cu-N complex) on the fish, Clarias gariepinus, exposed to mercuric chloride

Female catfish, Clarias gariepinus, were collected from the Nile River at Assiut region, were divided into 7 groups. The first group was left as control, and the second was treated with mercuric chloride (MC) for 3 weeks following by normal water for 1 week. The third, fourth and fifth groups were provided by MC (150 μg/ l of water). This treatment was continued for 3 weeks. Then, the fish were received CN instead of MC, for 1 week, with 15 and 25 mg CN/100 g wet food. The fifth fish group received diet supplemented with vit E (α-tocopherol) (100 mg/kg wet diet), for 1 week, instead of MC treatment. Vitamin E was used as standard antioxidant drug. Following 3 weeks of normal ambient water, the sixth and seventh aquaria received only CN for 1 week, with 15 and 25 mg CN respectively/100 g wet food, respectively. At the end of the experiment, Samples of liver, kidneys (posterior part), gills (right gills) and ovary were excised. The measurement included the oxidative stress parameters: carbonyl protein and total peroxide and the antioxidant enzyme activities superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in all selected organs. MC treatment induced harmful effect in fish, probably due to its enhancing effect on reactive oxygen species (ROS) production in fish organs especially the respiratory and osmoregulatory organs namely gills. The result suggests that this gill damage may exert hypoxic case, anoxia for different organs and some Cu excretion resulting in a magnification of ROS overproduction. Also, the observed oxidative stress in ovary tissue of MC-treated fish may affect fish fertility. The addition of CN in fish diets could protect the fish C. gariepinus against MC-induced oxidative damage showing recovery of fish organs. It could suggest that the detoxifying mechanism of action of CN is mainly due to its scavenging activity of free radicals rather than tissue healing.

Pathogenicity and oxidative stress in Nile tilapia caused by Aphanomyces laevis and Phoma herbarum isolated from farmed fish

Identified (n = 17) and unidentified (n = 1) fish-pathogenic fungal species from 10 genera of Oomycetes and soil fungi were isolated from 40 infected freshwater fish samples of the species Oreochromis niloticus niloticus (Nile tilapia) and Clarias gariepinus (African catfish). Samples were collected from various fish farms in the Nile Delta, Egypt. Nile tilapia were tested in aquaria for their susceptibility to the commonest Oomycetes species, Aphanomyces laevis and Achlya klebsiana, and also against the 2 most prevalent pathogenic soil fungi, Paecilomyces lilacinus and Phoma herbarum. Two techniques were used: water bath exposure and intramuscular (subcutaneous) injection. Water bath exposure to the 2 species of Oomycetes caused greater mortalities of O. niloticus niloticus than intramuscular injection, but the reverse was true of the soil fungal species. Regardless of the infection method, the 2 Oomycetes species were more potent pathogens than the soil fungal species. In both gills and mytomal muscles of fish infected by A. laevis and P. herbarum, we measured and compared with controls the oxidative stress parameters total peroxide (TP), lipid peroxidation (LPO) and nitric oxide (NO), as well as levels of the antioxidants vitamin E and glutathione (GSH), and superoxide dismutase (SOD) and catalase (CAT) activities. Infection by these 2 fungal species through either spore suspension or spore injection significantly increased oxidative damage in gills and induced marked decrease in most studied antioxidants. In addition, both routes showed similar effects and A. laevis depressed the antioxidants CAT, vitamin E and GSH more than P. herbarum.

Organ specific antioxidant responses in golden grey mullet (Liza aurata) following a short-term exposure to phenanthrene

Phenanthrene (Phe) is among the most abundant and ubiquitous polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment as a result of human activities. Even so, the knowledge about its impact on fish health is still limited. In this study, the teleost Liza aurata was exposed to 0.1, 0.3, 0.9 and 2.7 microM Phe concentrations during 16 h. Enzymatic antioxidants such as selenium dependent glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and catalase (CAT), as well as a non-enzymatic antioxidant (glutathione - GSH) were quantified in three target organs - gill, kidney and liver. The lipid peroxidation (LPO) was also assessed as a marker of oxidative damage. GPx activity was decreased in gill (0.1 and 0.9 microM), whereas in the liver it was increased (0.3-2.7 microM). GST activity was decreased in kidney (0.3-2.7 microM) and CAT activity was increased in gill after 0.9 microM exposure. GSH content was significantly increased in gill by the lowest concentration and in liver by all Phe concentrations. Despite the antioxidant defense responses, LPO increased in gill (0.3-2.7 microM), kidney (0.1 microM) and liver (0.1 and 2.7 microM). These results revealed organ specific antioxidant defenses depending on the Phe concentration. Liver demonstrated a higher adaptive competence expressed as antioxidant defenses activation, namely GSH and GPX. The lower vulnerability of the kidney to oxidative damage (compared to gill and liver) seems to be related to its higher antioxidant basal levels. Globally, current data highlight the Phe potential to induce oxidative stress and, consequently, to affect the well-being of fish.

Catalase inhibition by amino triazole induces oxidative stress in goldfish brain

The effects of in vivo inhibition of catalase by 3-amino 1,2,4-triazole (AMT) on the levels of damage products resulting from reactive oxygen species attack on proteins and lipids as well as on the activities of five antioxidant and associated enzymes were studied in the brain of goldfish, Carassius auratus. Intraperitoneal injection of AMT at a concentration of 0.1 mg/g wet weight caused a gradual decrease in brain catalase activity over 72 h, whereas higher AMT concentrations (0.5 or 1.0 mg/g) reduced catalase activity by about two-thirds within 5-10 h. AMT effects on antioxidant enzyme activities and oxidative stress markers were studied in detail using fish treated with 0.5 mg/g AMT for 24 or 168 h. The levels of thiobarbituric acid-reactive substances (a lipid damage product) increased 6.5-fold by 24 h after AMT injection but fell again after 168 h. The content of carbonylproteins (CP) also rose within 24 h (by approximately 2-fold) and remained 1.5-fold higher compared with respective sham-injected fish after 168 h. CP levels correlated inversely with catalase activity (R(2) = 0.83) suggesting that catalase may protect proteins in vivo against oxidative modification. The activities of both glutathione peroxidase and glutathione-S-transferase increased by approximately 50% and 80%, respectively, in brain of AMT-treated fish and this might represent a compensatory response to lowered catalase activity. Possible functions of catalase in the maintenance of prooxidant/antioxidant balance in goldfish brain are discussed.

Effects of horminone on liver mixed function mono-oxygenases and glutathione enzyme activities of Wistar rat

The present study reports on the effects of horminone on serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, on hepatic cytochrome P450 (P450) and cytochrome b5 (cyt b5) contents and on the activities of NADPH-cytochrome P450 reductase (NR), mixed function mono-oxygenases (MFO), glutathione-S-transferase (GST) and glutathione reductase (GR) of Wistar male rat. Horminone is a diterpenoid quinone (7,12-dihydroxyabiet-8,12-diene-11,14-dione) present in several species of the Labiatae family and used as medicinal plants in folk medicine. In this study, horminone was administered by the intraperitoneal route (i.p.) at a concentration of 1 or 10 mg/kg to each group of six mice, using water as a vehicle. On the one hand, results showed that horminone increased serum ALT and AST levels and cyt b5 content and induced the activities of ethylmorphine N-demethylase (EMD). On the other hand, horminone decreased P450 content and inhibited the activities of 7-ethoxyresorufin O-deethylase (ERD), 7-ethoxycoumarin O-deethylase (ECD), aniline 4-hydroxylase (AH) and NR. Based on these results, the possibility of toxic effects occurring after administration of plant extracts containing horminone must be considered.

Effect of dietary vitamin C and catalase inhibition of antioxidants and molecular markers of oxidative damage in guinea pigs

Guinea pigs were fed for five weeks with two diets with different levels of vitamin C, low (33 mg of Vit C/Kg diet) and high (13,200 mg of Vit C/Kg of diet). Catalase was inhibited with 3-amino-1,2,4-triazole (AT) in half of the animals from each dietary group. AT caused an almost complete depletion of liver catalase activity (90%) in both dietary groups. Vitamin C supplementation increased total glutathione peroxidase activity and tissue vitamin C level and decreased levels of protein carbonyls and malondialdehyde (MDA) in both treated and non-treated animals. This vitamin C supplementation did not change any of the other antioxidant defences studied. Our results show that dietary vitamin C supplementation increases global antioxidant capacity and decreases endogenous oxidative damage in the guinea pig liver under normal non-stressful conditions. This supports the protective value of dietary antioxidant supplementation.

Maximum life span in vertebrates: relationship with liver antioxidant enzymes, glutathione system, ascorbate, urate, sensitivity to peroxidation, true malondialdehyde, in vivo H2O2, and basal and maximum aerobic capacity

In order to help clarify whether free radicals are implicated or not in the evolution of maximum life span (MLSP) of animals, a comprehensive study was performed in the liver of various vertebrate species. Strongly significant negative correlations against MLSP were found for hepatic catalase, Se-dependent and -independent glutathione peroxidases, and GSH, whereas superoxide dismutase, glutathione reductase, ascorbate, uric acid, GSSG/GSH, in vitro peroxidation (TBA-RS), and in vivo steady-state H2O2 concentration in the liver did not correlate with MLSP. Superoxide dismutase, catalase, glutathione peroxidase, and GSH results were in agreement with those independently reported by other authors, whereas the rest of our data are reported for the first time. Potential limitations arising from the use of animals of different vertebrate Classes were counterbalanced by the possibility to study animals with very different MLSPs and life energy potentials. Furthermore, the results agreed with previous data obtained using only mammals. Since liver GSSG/GSH, peroxidation, and specially H2O2 concentration were similar in species with widely different MLSPs, it is suggested that the decrease in enzymatic H2O2 detoxifying capacity of longevous species represents an evolutionary co-adaptation with a smaller in vivo rate of free radical generation. We propose the possibility that maximum longevity was increased during vertebrate evolution by lowering the rate of free radical recycling in the tissues.

Simultaneous induction of sod, glutathione reductase, GSH, and ascorbate in liver and kidney correlates with survival during aging

Catalase was continuously inhibited with aminotriazole in the liver and kidney during 33 months in large populations of old and young frogs in order to study the effects of the modification of the tissue antioxidant/prooxidant balance on the life span of a vertebrate species showing an oxygen consumption rate similar to that of humans. Free-radical-related parameters were measured during three consecutive years at 2.5, 14.5, and 26.5 months of experimentation. Aging per se did not decrease antioxidant enzymes and did not increase peroxidation (thiobarbituric acid positive substances, or high-pressure liquid chromatography [HPLC]-malondialdehyde), either cross sectionally or longitudinally. Long-term catalase inhibition leads to time-dependent increases (100-900%) of endogenous superoxide dismutase, GSH, ascorbate, and especially glutathione reductase at 2.5 and 14.5 months of experimentation. This was positively correlated with a higher survival of treated animals (91% in treated versus 46% in controls at 14.5 months of experimentation). The loss of those inductions after 26.5 months leads to a sharp increase in mortality rate. The results show for the first time that simultaneous induction of various tissue antioxidant enzymes and nonenzymatic antioxidants can increase the mean life span of a vertebrate animal. It is concluded that the tissue antioxidant/prooxidant balance is a strong determinant of mean life span.

Lung glutathione reductase induction in aging catalase-depleted frogs correlates with early survival throughout the life span

A comprehensive experimental study on free radical-related parameters was performed in the lung throughout the life span of 220 initially young or old frogs. No age related differences were found transversely or longitudinally for lung superoxide dismutase, catalase, Se-dependent and -independent glutathione peroxidases, glutathione reductase, GSH, GSSG, or GSSG/GSH ratio. Continuous catalase depletion with aminotriazole led to glutathione reductase induction in the lung after 14.5 months of experimentation. This was accompanied by a great increase in survival rate of treated animals in relation to controls (especially in the old group). After 26.5 months of experimentation, glutathione reductase induction was lost and GSSG/GSH values tended to increase. This was followed by a 3-month long period of acute decrease in survival rate of treated animals. It is suggested that a high antioxidant/prooxidant balance is of protective value against causes of early death and can possibly be used in the future (when appropriately controlled) to increase the number of healthy years of the normal life span.

Brain glutathione reductase induction increases early survival and decreases lipofuscin accumulation in aging frogs

Brain catalase was continuously depleted throughout the life span starting with a large population of initially young and old frogs. Free radical-related parameters were measured in the brain tissue once per year after 2.5, 14.5, and 26.5 months of experimentation. Brain lipofuscin accumulation was observed after 14.5 and 26.5 months, and survival was continuously followed during 33 months. The age of the animal did not decrease endogenous antioxidants nor increase tissue peroxidation either in cross-sectional or longitudinal comparisons. Continuous catalase depletion similarly affected young and old animals, inducing glutathione reductase, tending to decrease oxidized glutathione/reduced glutathione (GSSG/GSH) ratio, decreasing lipofuscin accumulation in the brain, and increasing survival from 46% to 91% after 14.5 months. At 26.5 months of experimentation the loss of the glutathione reductase induction in catalase-depleted animals was accompanied by the presence of higher lipofuscin deposits than in controls and was followed by a great increase in mortality rate. Even though the maximal life span (7 years) was the same in the control and treated animals which were already old (4.2 years) at the beginning of the experiment, the treated animals showed a strong reduction in the rates of early death. It is proposed that the maintenance of a high antioxidant/prooxidant balance in the vertebrate brain greatly increases the probability of the individual to reach the final segments of its species-specific life span.