Tea polyphenol alleviate Aeromonas hydrophila- induced intestinal physical barrier damage in grass carp (Ctenopharyngodon idella)

This study aimed to investigate the effects of tea polyphenol (TP) supplementation on attenuating Aeromonas hydrophila induced intestinal barrier function injury in fish. A total of 540 healthy grass carp (187.49 +/- 0.66 g) were randomly divided into six groups with three replicates and fed TP-supplemented diets at 0, 40, 80, 120, 160 and 200 mg/kg for 60 days. After the growth trial, 24 fish per group were randomly selected for a challenge test with A. hydrophila for 6 days. The results indicated that an appropriate level of TP (120 mg/kg diet) repair damaged the intestinal morphology of fish induced by A. hydrophila. Additionally, appropriate level of TP ameliorated the intestinal apical junctional complex partly, which was partly related to the up-regulation of the expressions of tight junction and adherent junction proteins via the RhoA/ROCK pathway in the fish intestine. Based on the results of this research, dietary TP supplementation possesses a protective function of the intestinal physical barrier in fish against A. hydrophila, making TP a functional feed additive for aquaculture and providing a solution for the issue of hazards to human health caused by antibiotic residues in aquatic food.