Benjámin Kövesi

Changes of lipid peroxidation and glutathione redox system, and expression of glutathione peroxidase regulatory genes as effect of short-term aflatoxin B1 exposure in common carp

&NA; Lipid peroxidation, glutathione content, glutathione peroxidase activity and gene expression of transcription factors, glutathione peroxidase, glutathione synthetase and glutathione reductase was investigated in common carp liver. Short term (24 h) exposure of aflatoxin B1 at different doses (100, 200 and 400 &mgr;g AFB1 kg−1 feed) was used. It was found that conjugated dienes and trienes elevated after 16 h, while thiobarbituric acid reactive substances content increased only at the lowest dose after 16 and 24 h of exposure. Glutathione content showed higher levels than control after 16 h of exposure and glutathione peroxidase (GPx4) activity was higher in all of the AFB1 treated than the control group after 8 h of exposure. Gene expression of transcription factors showed dual response. Expression of keap1 gene down‐regulated after 8 h and 16 h and nrf2 gene after16 h, but up‐regulated after 24 h of exposure in the lowest, and highest dose groups. Expression of gpx4a and gpx4b genes down‐regulated after 8 h and induction was found after 16 and 24 h of exposure, irrespective of the dose. The results indicated that low dose of AFB1 provokes oxidative stress earlier than higher doses, which activated the Keap1‐Nrf2 pathway. At higher doses this pathway activated later, but preformed GPx4 effectively prevented lipid peroxidation. HighlightsShort term exposure of aflatoxin B1 is used in common carp as pro‐oxidant effect.Lipid peroxidation parameters coincide with the transit time of feed particles.Glutathione redox system responded rapidly and firmly.Analysed genes showed dual response after aflatoxin B1 exposure.The results indicated that low dose of AFB1 provokes oxidative stress earlier.

Short-term effects of T-2 toxin or deoxynivalenol on glutathione status and expression of its regulatory genes in chicken

Short-term (48-hour) effects of 3.74/1.26 mg kg-1 T-2/HT-2 toxin or 16.12 mg kg-1 DON in feed were investigated in the liver of three-week-old cockerels (body weight: 749.60 ± 90.98 g). Markers of lipid peroxidation showed no significant changes. At hour 24, glutathione content in the T-2/HT-2 toxin group was significantly higher than in the control. Glutathione peroxidase activity was significantly higher than the control at hour 24 in the T-2/H-2 toxin group and at hour 48 in the DON group. In the DON group, expression of the glutathione peroxidase 4 gene (GPX4) was significantly lower than in the control at hours 12 and 14, and higher at hour 48. Expression of the glutathione reductase gene (GSR) was significantly lower than in the control at hour 12 in the T-2/HT-2 toxin group, and at hours 12, 24 and 48 in the DON group. However, at hour 36 higher GSR expression was measured in the DON group. Due to the effect of both trichothecenes, expression of the glutathione synthetase gene (GSS) was significantly lower than in the control at hours 24 and 48. In conclusion, T-2/HT-2 toxin and DON had a moderate short-term effect on free radical formation. T-2/HT-2 toxin induced more pronounced activation of the glutathione redox system than did DON.

Multi-trichothecene mycotoxin exposure activates glutathione-redox system in broiler chicken

ABSTRACT Co‐occurrence of mycotoxin contamination of feeds is a frequent problem, therefore the purpose of this study was to evaluate the combined effect of T‐2 toxin and deoxynivalenol (DON) on lipid peroxidation, parameters and regulation of the glutathione redox system in broiler chickens in a sub‐chronic (7 day) study. The applied doses were: low mix: 0.23mg T‐2 toxin and 4.96mg DON/kg feed; medium mix: 1.21mg T‐2 toxin and 12.38mg DON/kg feed; and high mix: 2.42 T‐2 toxin and 24.86mg DON/kg feed. Liver samples were taken on days 0, 1, 2, 3, and 7 of the feeding trial. Lipid peroxidation decreased significantly as compared to the control on days 3 and 7 as effect of low and high doses, which can be related to the activation of the antioxidant system, which is supported by the elevated glutathione peroxidase activity and reduced glutathione concentration as compared to the control on day 3 in the medium and high dose groups. Gene expression of glutathione peroxidase 4 (GPX4) elevated on day 1 in a dose dependent manner, and showed continuous elevation in the highest dose group thereafter. The results suggested that common exposure of T‐2 toxin and DON induced oxidative stress in the liver of broiler chickens, which activated the enzymatic antioxidant system, and consequently decreased lipid peroxidation. HIGHLIGHTSCommon short‐term exposure to T‐2 toxin and DON decreased their known individual effect on feed refusal.Also, it was induced mild oxidative stress in the liver of chicken and increased expression of glutathione peroxidase 4 gene.Glutathione redox system responded rapidly and firmly.

Short-term effects of T-2 toxin or deoxynivalenol on lipid peroxidation and the glutathione system in common carp

The purpose of this study was to investigate the short-term effects of a single oral dose of T-2 and HT-2 toxin at 0.15, 0.33 and 1.82 mg kg-1 body weight, or deoxynivalenol (DON) and 15-acetyl-DON at 0.13, 0.31 and 1.75 mg kg-1 body weight in common carp. Conjugated dienes and trienes (the early markers of lipid peroxidation) were elevated in all DON-treated groups at the 16th hour, while thiobarbituric acid reactive substances (TBARS; termination marker) were increased at the highest dose of DON at the 16th and 24th hours. T-2 toxin did not cause changes in these parameters. Glutathione content and glutathione peroxidase activity showed higher levels at the 16th hour as the effect of both mycotoxins. The expression of glutathione peroxidase (GPx4) genes (gpx4a and gpx4b) revealed a dual response. Downregulation was observed at the 8th hour, followed by an induction at the 16th hour, at the lowest dose of both mycotoxins. Higher doses revealed long-drawn emergence and an elevation was observed only at the 24th hour. However, at the lowest and highest doses of DON or T-2 toxin the changes in gene expression were delayed, which may be related to the low oxidative stress response, as suggested by the expression profiles of the nrf2, keap1, gpx4a and gpx4b genes.