Oxidative Stress In Rainbow Trout Research Articles

Effects of water quality on palladium-induced olfactory toxicity and bioaccumulation in rainbow trout (Oncorhynchus mykiss).

Through emission processes, palladium (Pd) particulates from industrial sources are introduced into a range of ecosystems including freshwater environments. Despite this, research on Pd-induced bioaccumulation, uptake, and toxicity is limited for freshwater fishes. Unlike other metals, there are currently no regulations or protective guidelines to limit Pd release into aquatic systems, indicating a global absence of measures addressing its environmental impact. To assess the olfactory toxicity potential of Pd, the present study aimed to explore Pd accumulation in olfactory tissues, olfactory disruption, and oxidative stress in rainbow trout (Oncorhynchus mykiss) following waterborne Pd exposure. Olfactory sensitivity, measured by electro-olfactography, demonstrated that Pd inhibits multiple pathways of the olfactory system following 96 h of Pd exposure. In this study, the concentrations of Pd for inhibition of olfactory function by 20% (2.5 μg/L; IC20) and 50% (19 μg/L; IC50) were established. Rainbow trout were then exposed to IC20 and IC50 Pd concentrations in combination with varying exposure conditions, as changes in water quality alter the toxicity of metals. Independent to Pd, increased water hardness resulted in decreased olfactory perception owing to ion competition at the olfactory epithelium. No other environmental parameter in this study significantly influenced Pd-induced olfactory toxicity. Membrane-associated Pd was measured at the olfactory rosette and gill following exposure; however, this accumulation did not translate to oxidative stress as measured by the production of malondialdehyde. Our data suggest that Pd is toxic to rainbow trout via waterborne contamination near field-measured levels. This study further demonstrated Pd bioavailability and uptake at water-adjacent tissues, adding to our collective understanding of the toxicological profile of Pd. Taken together, our results provide novel insights into the olfactory toxicity in fish following Pd exposure. Integr Environ Assess Manag 2024;20:1407-1419. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Effects of Acute and Subchronic Waterborne Thallium Exposure on Ionoregulatory Enzyme Activity and Oxidative Stress in Rainbow Trout (Oncorhynchus mykiss).

The mechanisms of acute (96-hour) and subchronic (28-day) toxicity of the waterborne trace metal thallium (Tl) to rainbow trout (Oncorhynchus mykiss) were investigated. Specifically, effects on branchial and renal ionoregulatory enzymes (sodium/potassium adenosine triphosphatase [ATPase; NKA] and proton ATPase) and hepatic oxidative stress endpoints (protein carbonylation, glutathione content, and activities of catalase and glutathione peroxidase) were examined. Fish (19-55 g) were acutely exposed to 0 (control), 0.9 (regulatory limit), 2004 (half the acute median lethal concentration), or 4200 (acute median lethal concentration) µg Tl L-1 or subchronically exposed to 0, 0.9, or 141 (an elevated environmental concentration) µg Tl L-1 . The only effect following acute exposure was a stimulation of renal H+ -ATPase activity at the highest Tl exposure concentration. Similarly, the only significant effect of subchronic Tl exposure was an inhibition of branchial NKA activity at 141 µg Tl L-1 , an effect that may reflect the interaction of Tl with potassium ion handling. Despite significant literature evidence for effects of Tl on oxidative stress, there were no effects of Tl on any such endpoint in rainbow trout, regardless of exposure duration or exposure concentration. Elevated basal levels of antioxidant defenses may explain this finding. These data suggest that ionoregulatory perturbance is a more likely mechanism of Tl toxicity than oxidative stress in rainbow trout but is an endpoint of relevance only at elevated environmental Tl concentrations. Environ Toxicol Chem 2024;43:87-96. © 2023 SETAC.

EFFECTS OF DIETARY YEAST Β-1.3/1.6-GLUCANS ON LIPID PEROXIDATION IN THE HEPATIC AND CARDIAC TISSUES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM), EUROPIAN WHITEFISH (COREGONUS LAVARETUS L.), AND GRAYLING (THYMALLUS THYMALLUS L.)

Dietary β-glucans may be a useful tool to prime the host immune system and increase resistance against invading pathogens as the β-glucans influence the immune response. This prompted us to investigate the effects of dietary yeast β-1,3/1,6-D-glucans supplemented for a 14-day feeding period on liver and cardiac function and the oxidative mechanisms underlying these effects. We assessed relevant lipid peroxidation in the hepatic and cardiac tissue of rainbow trout (Oncorhynchus mykiss), European whitefish (Coregonus lavaretus), and graylings (Thymallus thymallus) after a 14-day period of supplementation with β-glucans. Thirty healthy grayling weighing 34.9 ± 1.9 g, thirty healthy rainbow trout weighing 55.9 ± 2.1 g, and thirty healthy European whitefish weighing 43.3 ± 2.7 g were used in the experiments. The fish were fed with a commercial basal diet at a rate of 1.5% body weight four times a day. After acclimation, the fish were randomly divided into six groups. The groups were fed for 14 days as follows: the control groups comprising grayling (n = 15), rainbow trout (n = 15), and European whitefish (n = 15) received a control basal diet and the β-glucan groups were fed with the Yestimun® food product at a dose of 1% of the basal feed (with 85% of β-1.3/1.6-glucans, Leiber GmbH, Bramsche, Germany). The basal feed was supplemented with 1% of Yestimun® powder (dose: 1 kg per 99 kg, w/w). This insoluble and highly purified preparation contains natural polysaccharides, e.g. β-1,3/1,6-D-glucans derived from Spent Brewers’ Yeast (Saccharomyces cerevisiae). Yeast cell walls typically contain approximately 30% of β-glucans of dry weight. Our results showed that feeding with low doses of β-glucans induced a decrease in TBARS levels in the hepatic and cardiac tissues of rainbow trout, andEuropean whitefish. Similarly, 14 days of feeding graylings with low doses of β-glucans resulted in a decrease in the TBARS levels both in the hepatic and cardiac tissues. This study confirms that dietary β-glucan is beneficial for promoting growth and enhancing antioxidant capacity against oxidative stress in rainbow trout, European whitefish, and graylings. Indeed, we cautiously hypothesized that feeding low β-glucans doses may help to boost antioxidant function, especially by the decrease of biomarkers of lipid peroxidation in the hepatic and cardiac tissues of these fish. Keywords: β-glucans, oxidative stress, lipid peroxidation, Thymallus thymallus, Oncorhynchus mykiss, Coregonus lavaretus

Ameliorating effects of dietary Haematococcus pluvialis on arsenic-induced oxidative stress in rainbow trout (Oncorhynchus mykiss) fillet

The current study was performed to investigate the protective effects of dietary Haematococcus pluvialis (H. pluvialis) on the oxidative stress induced by arsenic in rainbow trout (Oncorhynchus mykiss). The fish (20.70 ± 0.09 g) were fed with H. pluvialis at the levels of 0.28, 0.56, and 1.12 g 100 g−1 diet for 60 days. Then, each group was divided into two subgroups. In one of the subgroups, fish were exposed to arsenic challenge at a level of 9.1 mg/L. The other subset was used as the negative control. After the 96 h of toxicity test, protein and lipid oxidative levels, antioxidant-relevant gene expression as well as several chemical factors, including pH and peroxide value and moisture content, were evaluated in the fillet samples. Results showed that feeding with H. pluvialis decreased the levels of pH, peroxide value, as well as protein and lipid oxidation levels in treatment groups. Besides, the expression of antioxidant genes was significantly increased in the groups administrated with H. pluvialis. Based on the results of this study, feeding H. pluvialis attenuated the oxidative stress induced by arsenic in rainbow trout fillet through improving the antioxidant defense system.

The effect of Spirulina platensis meal on antioxidant gene expression, total antioxidant capacity, and lipid peroxidation of rainbow trout (Oncorhynchus mykiss).

The study was conducted to investigate the effect of diets containing 0, 2.5, 5, 7.5, and 10% S. platensis meal on total antioxidant capacity (TAC) and lipid peroxidation, as well as the expression of two antioxidant enzyme genes (SOD and CAT) in rainbow trout (Oncorhynchus mykiss). One hundred and eighty fish, with an average initial weight of 101 ± 8g, were cultured for 10weeks. At the end of experiment, lipid peroxidation significantly decreased in serum of fish fed with S. platensis and fish fed with 5, 7.5, and 10% microalgae showed a significantly lower value compared to control and 2.5%. Inclusion of 7.5 and 10% S. platensis in diet also decreased lipid peroxidation in liver. TAC significantly increased with increasing level of S. platensis. Expression level of superoxide dismutase (SOD) and catalase (CAT) genes significantly increased in the fish liver after administration of microalgae and fish fed with 10% S. platensis in diet showed the highest level compared to the other treatments. The present study reveals that inclusion of 10% S. platensis in diet can decrease oxidative stress in rainbow trout. Therefore, S. platensis can be used as potential antioxidant for fish farming.

Methylmercury-induced oxidative stress in rainbow trout (Oncorhynchus mykiss) liver: ameliorating effect of vitamin C.

The present study was undertaken to evaluate methylmercury-induced alterations in hepatic enzymes and oxidative stress markers in liver tissue of rainbow trout (Oncorhynchus mykiss) by using a perfusion method, and to explore possible protective effect of vitamin C against these alterations. Forty-eight fish were divided into six groups containing control, test, and amelioration groups. The liver of fish in the test groups were exposed to different doses of methylmercury, i.e., 0.6, 1.2, and 2.4μgL(-1), respectively, for 120min. In the amelioration group, liver was treated with vitamin C (17.2μgL(-1)) along with high dose (2.4μgL(-1)) of methylmercury. The results of the present study showed that exposure with 0.6, 1.2, and 2.4μgL(-1) of methylmercury significantly increased (p < 0.05) hepatic enzyme activities (alanine transaminase (ALT), aspartate transaminase (AST), and Lactate dehydrogenase (LDH)) and malondialdehyde (MDA) level, as a marker of lipid peroxidation. On the other hand, the concentration of reduced glutathione (GSH) and total antioxidant capacity of the liver decreased (p < 0.05) in the methylmercury-exposed groups when compared to the control group. Pearson's correlation analysis revealed a positive correlation between MDA concentration and ALT, AST, and LDH activities in the methylmercury groups, suggesting that the enhanced lipid peroxidation may be linked to hepatic damage caused by methylmercury. Treatment with vitamin C in methylmercury-exposed group led to a significant decrease (p < 0.05) in MDA concentration and hepatic enzyme activities and significant increase (p < 0.05) in levels of GSH and total antioxidant capacity. The values of measured parameters in the methylmercury + vitamin C group were comparable to those of the control group. The results of the present study demonstrated that methylmercury exposure induces oxidative stress in the liver of rainbow trout and treatment with vitamin C can protect fish liver against this oxidative insult.

Oxidative stress in rainbow trout ( Oncorhynchus mykiss) exposed to sewage treatment plant effluent

Effluents from sewage treatment plants (STPs) can be regarded as “hot spots” of discharge releasing large amounts of chemicals into the aquatic environment. Many of these compounds are toxic to organisms due to their ability to form reactive oxygen species (ROS) and cause oxidative stress. In order to investigate if STP effluents contain compounds that may cause oxidative stress, rainbow trout ( Oncorhynchus mykiss) were exposed to effluent from a Swedish STP at different dilutions in a flow-through system. Antioxidant enzymes analyzed were glutathione reductase (GR), catalase (CAT) and DT-diaphorase (DTD). Catalytic activities of CYP1A (EROD) and the conjugating enzyme glutathione- S transferase (GST) were also analyzed. Results indicate that the effluent contains prooxidants since the activities of the antioxidant enzymes GR, CAT, and DTD were all elevated after 5 days of exposure. A prolonged exposure resulted in an inhibition of DT diaphorse activity, suggesting a depleted cellular ROS defence. EROD activities increased in a dose- and time-dependent manner, which suggests the presence of aryl hydrocarbon receptor (AHR) ligands such as polycyclic aromatic hydrocarbons (PAHs) in the effluent. These results indicate that STPs do not have the capacity to biodegrade harmful chemicals sufficiently to protect the aquatic environment. However, STPs are designed to remove nutrients and not persistent pollutants from the sewage and effort should be made to diminish the amount of chemicals entering the sewage in the first place.

Zinc picolinate supplementation decreases oxidative stress in rainbow trout (Oncorhynchus mykiss)

The effect of zinc picolinate (ZnPic) supplementation at various levels (0, 30, 60 mg/kg of diet) on growth, feed intake, feed efficiency and concentrations of malondialdehyde (MDA), Zn, Cu and Mn, and serum alkaline phosphatase (ALP) activity of rainbow trout was evaluated. Ninety 0+ y-old rainbow trout were randomly assigned to 3 treatment groups, 2 replicates of 15 fish each. The fish were fed either a basal diet or the basal diet supplemented with either 30 or 60 mg of Zn/kg of diet. Body weight gain, feed intake and feed efficiency were not significantly influenced by the dietary zinc picolinate supplementation. Serum alkaline phosphatase activity concentration linearly increased (P=0.01), whereas serum, liver and whole body malondialdehyde (MDA) concentrations linearly decreased as dietary ZnPic supplementation increased (P=0.001). Increasing dietary zinc supplementation linearly increased serum (P=0.01) and whole body Zn concentrations (P=0.05). However, serum and whole body Cu and Mn concentrations did not change as dietary ZnPic supplementation increased. Results of the present study indicate that zinc picolinate supplementation significantly decreased oxidative stress in rainbow trout and did not impact growth or feed consumption.

Rubber additives induce oxidative stress in rainbow trout

Several studies have demonstrated the toxicity of rubber leachate, mainly from rubber tires, to aquatic organisms. In the present study rainbow trout ( Oncorhynchus mykiss) were exposed to water provided to aquaria through a rubber hose. Increased hepatic ethoxyresorufin- O-deethylase (EROD) activity, and glutathione reductase (GR) activity were observed in the exposed fish. Two common rubber additives, 2-mercaptobenzothiazole (MBT) and diphenylamine (DPA) and structurally related compounds, were identified by chemical analyses of water samples as were hydroxylated polycyclic aromatic hydrocarbons. Metabolites of these compounds were also detected in the bile of exposed fish, as were some of the parent compounds. In a following experiment , we injected rainbow trout with DPA or MBT. Both compounds affected total glutathione (tGSH) concentration in liver and MBT caused an increase in hepatic GR and glutathione S-transferase (GST) activity as well. In DPA injected fish, hydroxylated DPA was the main metabolite in the bile. Our results indicate that rubber chemicals may leach into the water surroundings where they can be taken up and metabolised by fish. Some of these chemicals can lead to up-regulation of antioxidant defences as demonstrated with DPA and MBT injections.

Effects of redox cycling compounds on glutathione content and activity of glutathione-related enzymes in rainbow trout liver

In fish, as in other aerobic organisms, glutathione and glutathione-related enzymes are important components in the defences against oxidative stress. To study if hepatic glutathione levels and/or activities of glutathione-related enzymes can act as indicators of oxidative stress in fish, we injected rainbow trout ( Oncorhynchus mykiss) intraperitoneally with paraquat (PQ), menadione (MD), naphthazarin (DHNQ), or β-naphthoflavone (β-NF), all known to cause a rise in reactive oxygen species (ROS). After 2 and 5 days of exposure, we measured the activities of hepatic glutathione peroxidase (GPox), glutathione S-transferase (GST), γ-glutamylcysteine synthetase (GCS), and glutathione reductase (GR). We also measured total glutathione (tGSH) and oxidised glutathione (GSSG) in the liver of fish treated with PQ and MD. All chemicals caused an increase in GR activity after 5 days, which ranged from 160% in fish treated with β-NF to 1500% in fish treated with PQ. All chemicals except β-NF caused moderate elevation in GST activity; GPox activity was lower in fish treated with DHNQ and MD, while GCS activity increased twofold in the fish treated with DHNQ, without being affected by β-NF, PQ or MD. After 5 days of treatment with PQ or MD, tGSH content was elevated. Our findings demonstrated that of the parameters included in the study, GR activity was the most responsive to treatment with redox cycling compounds, indicating that GR activity is a promising biomarker of such compounds and possibly indicating oxidative stress in rainbow trout.

Effect of astaxanthin rich red yeast ( Phaffia rhodozyma) on oxidative stress in rainbow trout

The antioxidative biological effect of dietary red yeast, Phaffia rhodozyma, which is rich in astaxanthin, on rainbow trout, Oncorhynchus mykiss, was examined. The levels of serum transaminase (glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase) activities and of lipid peroxides (LPO) of fish fed oxidized oil were significantly higher than those of the control fish fed non-oxidized oil. However, the supply of red yeast considerably decreased both enzyme activities and LPO level. Furthermore, the serum lipid (triglycerides, total cholesterol and phospholipids) concentrations were also significantly decreased. Especially, the serum triglyceride level of fish fed the red yeast was as low as that of the control. It was also observed that there were no significant differences in muscle LPO levels between the fish fed red yeast and the control. The present results suggest for the first time that dietary red yeast may effectively suppress the LPO generation of tissue and normalize liver function as well as improving muscle pigmentation of trout. Thus, red yeast should have a reducing effect on oxidized oil-induced oxidative stress in fish.