ACTIVITY OF ANTIOXIDANT ENZYMES IN THE CARDIAC AND HEPATIC TISSUES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM) FED A DIET SUPPLEMENTED WITH Β-GLUCANS

This study investigates the effects of dietary β-glucans on the activity of key antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx)] in the hepatic and cardiac tissues of rainbow trout (Oncorhynchus mykiss Walbaum). Supplementation with β-glucans significantly modulated catalase (CAT) and glutathione peroxidase (GPx) activities in both tissues, suggesting enhanced antioxidant defence mechanisms. In the hepatic tissue, a 264.6% increase in CAT activity (p < 0.05) and a 311% increase in GPx activity (p < 0.05) was observed, indicating enhanced hydrogen peroxide detoxification and oxidative stress resistance. A similar enhancement of antioxidant capacity was observed in the heart, with an increase in cardiac CAT activity of 135.7% (p < 0.05). Although changes in superoxide dismutase (SOD) activity were not statistically significant, a trend of decreased hepatic SOD activity and increased cardiac SOD activity was observed, potentially reflecting tissue-specific oxidative defense strategies. Glutathione reductase (GR) activity decreased in both tissues, albeit not significantly, suggesting possible adaptations in the glutathione cycle. The findings of this study emphasise the tissue-specific modulation of antioxidant pathways by dietary β-glucans and their potential role in enhancing oxidative stress resistance in aquaculture species. The data suggest that dietary β-glucans induce tissue-specific modulations of antioxidant enzyme activities in rainbow trout, potentially enhancing oxidative resilience in liver and heart tissues. These effects are likely to arise from the bioactive properties of β-glucans, which are known to influence immune and oxidative defence pathways. It is recommended that future studies focus on long-term feeding trials and the inclusion of additional biomarkers to facilitate a comprehensive understanding of the physiological effects of β-glucan supplementation.