Modulation of immune parameters and antioxidant defense in zebrafish (Danio rerio) using dietary apple cider vinegar

In the present study, the effects of apple cider vinegar (ACV) on some immunological parameters and expression of genes related to immune system, growth and antioxidant system in zebrafish were evaluated. Fish (mean weight 67 +/- 3.5 mg) were fed four diets with ACV at 0, 1.5, 3 and 4.5% for 8 weeks. At the end of the trial, no effects were observed on the growth performance and survival rates of fish fed ACV. Significantly higher complement titer and alkaline phosphatase activity in fish fed 3 and 4.5% ACV were observed in comparison with the control group (P < .05). Lysozyme activity was significantly (P < .05) higher in fish fed 4.5% ACV compared to the control group whereas gene expression analysis by real-time PCR showed that gene encoding lysozyme was significantly upregulated in fish fed 1.5% ACV supplemented diet (P < .05). Interleukin 8 (IL8) gene expression was also significantly upregulated in fish fed with 4.5% ACV (P < .05). Meanwhile, diets with 3 and 4.5% ACV caused up-regulation of ghrelin, catalase and glutathione S-reductase genes in fish homogenates (P < .05). In conclusion, diets supplemented with ACV especially at 4.5%-had the potential to improve immunological parameters and gene expression related to immunity, antioxidant system and growth performance in zebrafish.