Protective effect of propolis against oxidative stress and immunosuppression induced by oxytetracycline in rainbow trout (Oncorhynchus mykiss, W.)

Dietary administration of the probiotic SpPdp11: Effects on the intestinal microbiota and immune-related gene expression of farmed Solea senegalensis treated with oxytetracycline

Few antimicrobials are currently authorised in the aquaculture industry to treat infectious diseases. Among them, oxytetracycline (OTC) is one of the first-choice drugs for nearly all bacterial diseases. The objective of this study was to evaluate the effect of the dietary administration of OTC both alone and jointly with the probiotic Shewanella putrefaciens Pdp11 (SpPdp11) on the intestinal microbiota and hepatic expression of genes related to immunity in Senegalese sole (Solea senegalensis) juveniles. The results demonstrated that the richness and diversity of the intestinal microbiota of fish treated with OTC decreased compared with those of the control group but that these effects were lessened by the simultaneous administration of SpPdp11. In addition, specimens that received OTC and SpPdp11 jointly showed a decreased intensity of the Denaturing Gradient Gel Electrophoresis (DGGE) bands related to Vibrio genus and the presence of DGGE bands related to Lactobacillus and Shewanella genera. The relationship among the intestinal microbiota of fish fed with control and OTC diets and the expression of the NADPH oxidase and CASPASE-6 genes was demonstrated by a Principal Components Analysis (PCA) carried out in this study. In contrast, a close relationship between the transcription of genes, such as NKEF, IGF-β, HSP70 and GP96, and the DGGE bands of fish treated jointly with OTC and SpPdp11 was observed in the PCA study. In summary, the results obtained in this study demonstrate that the administration of OTC results in the up-regulation of genes related to apoptosis but that the joint administration of OTC and S. putrefaciens Pdp11 increases the transcription of genes related to antiapoptotic effects and oxidative stress regulation. Further, a clear relationship between these changes and those detected in the intestinal microbiota is established.

Trichlorfon-induced haematological and biochemical changes in Cyprinus carpio: ameliorative effect of propolis

Trichlorfon is among the most commonly used products to treat fish parasites in aquaculture. We investigated the effectiveness of propolis in alleviating the toxicity of trichlorfon on haematological and oxidant/antioxidant parameters in carp Cyprinus carpio. Fish were exposed to sublethal concentrations (11 and 22 mg l-1) of trichlorfon, and propolis (10 mg kg-1 of fish weight) was simultaneously administered. At the end of 14 d administration, blood and tissue (liver, kidney, gill) samples were collected. Haematological changes (red and white blood cell count, haemoglobin concentration, haematocrit level and erythrocyte indices: mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration) were determined in the blood samples, while antioxidant parameters (malondialdehyde and reduced glutathione levels and superoxide dismutase, catalase and glutathione peroxidase activities) were evaluated in the liver, kidney and gill samples. Trichlorfon led to negative alterations in the haematological and antioxidant parameters investigated. The administration of propolis alleviated this effect and suggests that fish treated with trichlorfon improve their physiological status when fed a propolis-supplemented diet.

Transferability of oxytetracycline (OTC) from feed to carp muscle and evaluation of the antibiotic effects on antioxidant systems in liver and kidney

Oxytetracycline (OTC) is employed in fish farms to contest or prevent bacterial infections. We simulated an OTC treatment at therapeutic level (75 mg kg(-1)) and at higher doses (150, 300 mg kg(-1)) for 10 days. A withdrawal period of 10 days was considered for treated carp, carrying out the same chemical and biochemical analyses (total glutathione, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase and malondialdehyde). The aim was to obtain data related to the carryover in muscle and on variations in the antioxidant indicators in liver and kidney. The OTC residual levels in muscle showed a dose-response relationship. After 10 days of treatment at the recommended dose (75 mg kg(-1)), the mean value in muscle was 295 μg kg(-1). After 10 withdrawal days, residues in all treated groups were not entirely eliminated by fish. Residues of recommended 75 mg kg(-1) OTC dose were lower than the maximum permitted by EEC regulation: 100 μg kg(-1). Disturbance in the antioxidant systems in liver and kidney was recorded in (150, 300 mg kg(-1)) carp, as well as during the withdrawal period. A lowered superoxide dismutase activity and higher levels of catalase, glutathione peroxidase, glutathione reductase and glutathione were evaluated in liver, while in kidney only higher malondialdehyde and glutathione S-transferase concentrations were recorded for 300 mg kg(-1) dose. The therapeutic OTC dose exerted lower effects, and only in liver, enhancement of GPx and GR activities was recorded. After the withdrawal period, altered antioxidant responses in tissues were restored for all three OTC doses.

Malathion-induced changes in the haematological profile, the immune response, and the oxidative/antioxidant status of Cyprinus carpio carpio: protective role of propolis

The present study investigated the potential ameliorative effects of propolis against malathion toxicity in the blood and various tissues of carp. The fish were exposed to sublethal concentrations of malathion (0.5 and 1 mg/L) for 10 days, and propolis (10 mg/kg of fish weight) was simultaneously administered. Blood and tissue (liver, kidney, and gill) samples were collected at the end of the experiment and analysed to determine the haematological profile (red blood cell count, haemoglobin concentration, haematocrit level, and erythrocyte indices: mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration), immune response (white blood cell count, oxidative radical production, nitroblue tetrazolium (NBT) activity, total plasma protein and total immunoglobulin levels, and the phagocytic activity), and oxidant/antioxidant status (malondialdehyde and reduced glutathione levels and superoxide dismutase, catalase, and glutathione peroxidase activities) of the fish. The findings of this study demonstrate that malathion has a negative effect on the haematological parameters, immune response, and antioxidant enzyme activities of the fish. However, the administration of propolis ameliorated the malathion-induced toxic effects.

Protective effect of aquacultured flounder fish-derived peptide against oxidative stress in zebrafish

This study investigates the protective effect of aquacultured flounder fish-derived peptide (AFFP) against 2,2-azobis-(2-amidinopropane) hydrochloride (AAPH)-induced oxidative damage in a zebrafish model. Zebrafish embryos were evaluated for the protective effect by heartbeat rate, survival rate, ROS generation, lipid peroxidation, and cell death. In the results, the AAPH group showed a low survival rate, whereas the AFFP and AAPH co-treated group increased a survival rate. Also, AFFP dose-dependently reduced AAPH-induced intracellular ROS and lipid peroxidation, and decreased cell death in AAPH-induced zebrafish. These results revealed that AFFP could be used as a natural antioxidant, and that the zebrafish provides an alternative in vivo model to efficiently evaluate the antioxidative effects of peptides on fishes.

Toxic effects of malathion in carp, Cyprinus carpio carpio: protective role of lycopene

The present study was carried out in order to investigate the potential protective effects of lycopene against malathion-induced toxicity in carp. The fish were exposed to sublethal concentrations of malathion (0.5 and 1mgL(-1)) for 14 days, and lycopene (10mgkg(-1) of fish weight) was simultaneously administered. Samples of the blood and tissue (liver, kidneys, and gills) were collected at the end of the experimental period and their haematological profiles [red blood cell (RBC) counts, haemoglobin (Hb) concentrations, haematocrit (Ht) levels, and erythrocyte indices, including the mean corpuscular volume (MCV), the mean corpuscular haemoglobin (MCH) and the mean corpuscular haemoglobin concentration (MCHC)], immune responses [white blood cell (WBC) counts, oxidative radical production (nitroblue tetrazolium (NBT) activity), total plasma protein (TP) and total immunoglobulin (TI) levels and phagocytic activities (PA)] and oxidant/antioxidant statuses [malondialdehyde (MDA) levels, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, and reduced glutathione (GSH) concentrations] were analysed. The findings of the present study demonstrated that the exposure of carp to malathion resulted in alterations in the haematological profiles and immune responses, and lead to increased reactive oxygen species formation, resulting in oxidative damage and inhibition of the antioxidant capacities. However, the administration of lycopene prevented malathion-induced toxic effects.

Effects of oxytetracycline and amoxicillin on development and biomarkers activities of zebrafish (Danio rerio)

Antibiotics have been widely used in human and veterinary medicine to treat or prevent diseases. Residues of antibiotics have been found in aquatic environments, but their effects on fish have been not properly investigated. This work aimed to assess the sub-lethal effects of oxytetracycline and amoxicillin on zebrafish development and biomarkers. Embryos and adults were exposed during 96 h to amoxicillin and oxytetracycline following OECD guidelines. Tissues of adults and pools of embryos were used for catalase, glutathione-S-transferases and lactate dehydrogenase determinations. Amoxicillin caused premature hatching (48 h-EC50=132.4 mg/l) whereas oxytetracycline cause delayed hatching of embryos (72 h-EC50=127.6 mg/l). Moreover, both antibiotics inhibited catalase and induced glutathione-S-transferases in zebrafish adults. However, only oxytetracycline induced lactate dehydrogenase. Short-term effects of antibiotics were observed at high doses (mg/l) indicating that physiological impairment in fish populations is unlike to occur. However, effects of chronic exposures to low doses of ABs must be investigated.

The effect of lycopene on oxytetracycline-induced oxidative stress and immunosuppression in rainbow trout (Oncorhynchus mykiss, W.)

The aim of this study was to determine the effects of lycopene on oxytetracycline (OTC)-induced oxidative stress and immunosuppression in rainbow trout. The experimental fish analysed in this study were divided into 6 different experimental groups. Group 1 was the control group, and groups 2, 3 and 4 received corn oil, lycopene and OTC, respectively, for 14 days. Group 5 received OTC for 14 days after lycopene pre-treatment for 14 days, while group 6 received OTC for 14 days before lycopene post-treatment for 14 days. Blood and tissue samples were collected at the end of the experiment and analysed for the oxidant-antioxidant status and changes in the immune response. There was a significant increase in the malondialdehyde level, which is an index of lipid peroxidation, and a decrease in superoxide dismutase, catalase, and glutathione peroxidase activity as well as a decrease in the glutathione level in the blood, liver, kidney and spleen of OTC-treated fish. Glutathione-S-transferase activity was significantly increased in the blood, liver, kidney and spleen samples of the group that received OTC alone. OTC also appeared to suppress specific and nonspecific immune system parameters, such as the haematocrit, leucocyte count, oxidative radical production (nitroblue tetrazolium activity), total plasma protein and immunoglobulin levels and phagocytic activity. Pre- and post-treatment with lycopene attenuated the OTC-induced oxidative stress by significantly decreasing the tissue malondialdehyde level. The superoxide dismutase, catalase and glutathione peroxidase activities as well as the glutathione levels were significantly increased with lycopene administration, while glutathione-S-transferase activity was significantly decreased. Lycopene administration was also associated with a significant increase in the OTC-suppressed immune system parameters in fish. Thus, the present results suggest that pre- and post-treatment with lycopene (10 mg per kg fish weight, delivered orally) may alleviate OTC-induced oxidative stress and immunosuppression.

Protective role of propolis in chlorpyrifos-induced changes in the haematological parameters and the oxidative/antioxidative status of Cyprinus carpio carpio

The protective effect of propolis on haematological parameters and antioxidant status were evaluated in the blood and various tissues of carp exposed to chlorpyrifos (CPF). The fish were exposed to sublethal concentrations of CPF (0.040 and 0.080 mg/L) for 10 days, and propolis (10 mg per kg of fish weight) was simultaneously administered. Samples of the blood and tissue (liver, kidney, and gill) were collected at the end of the experiment and analysed for their oxidant-antioxidant status, including the malondialdehyde (MDA) levels, and the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activity. The samples were also measured for changes in the haematological parameters, such as the red blood cell (RBC) and white blood cell (WBC) counts, the haemoglobin concentration (Hb), the haematocrit (Ht) level, and the erythrocyte indices: the mean corpuscular volume (MCV), the mean corpuscular haemoglobin (MCH) and the mean corpuscular haemoglobin concentration (MCHC). The findings of this study demonstrated that CPF had a negative effect on the haematological parameters and the antioxidant enzyme activities of the fish; this toxic effect was neutralised by the administration of propolis. The present results suggest that propolis can be effective in the protection of CPF-induced toxicity in fish.