Effect of dietary barberry fruit (Berberis vulgaris) extract on immune function, antioxidant capacity, antibacterial activity, and stress-related gene expression of Siberian sturgeon (Acipenser baerii)

Abstract

Barberry fruit (BF) has a long history as a folk remedy due to its antimicrobial, anti-inflammatory, antioxidant, and cholagogic properties. This study was performed to determine the dietary effect of BF extract on serum and skin mucus immune parameters, antioxidant status, and stress-selected gene expression in Siberian sturgeon. One hundred and fifty fish (30 ± 1 g initial weight) were fed with different levels of BF extract including 0 (control), 150, 300, 600, and 750 mg kg−1 for 8-week. After the feeding trial, the counts of white blood cells and lymphocytes were increased in BF-added groups compared to the control group (P < 0.05). The highest levels of serum complement component 4, lysozyme activity, and alternative complement were obtained in 750 mg kg−1 BF extract treatment (P < 0.05). The highest activities of protease, alkaline phosphatase, and esterase were obtained in the skin mucus samples of the fish fed with 750 mg kg−1 BF extract (P < 0.05). The group fed diets supplemented with 600 and 750 mg kg−1 BF extract showed the highest mucus lysozyme activity (P < 0.05). The activities of glutathione peroxidase and superoxide dismutase were increased in fish treated with different levels of BF extract (P < 0.05), while malondialdehyde content was decreased in BF-added groups compared to the control group (P < 0.05). Heat shock protein and cytochrome P450 mRNA expressions were lowest in the 750 mg kg−1 BF extract treatment group, while the highest levels of both genes were found in the control group (P < 0.05). The results showed marked improved antibacterial capacity of Siberian sturgeon fed dietary BF against Streptococcus iniae, Yersinia ruckeri, Escherichia coli, Listeria monocytogenes, Aeromonas hydrophila, and Lactococcus garvieae. This study unveiled the promising results of dietary BF extract, especially at 750 mg kg−1, in the regulation of immune and antioxidant defense systems along with the stress responses in Siberian sturgeon.