Inhibition of TNBS-induced intestinal inflammation in crucian carp (Carassius carassius) by oral administration of bioactive Bioactive food derived peptides

Intestinal enteritis is a main issue in crucian carp production which results in massive economic loss. Traditional antibiotics used for disease prevention of crucian carp (Carassius carassius) have been banned, thus an alternative approach needs to be identified. In this study, the bioactive peptide was evaluated as a diet supplement for preventing intestinal inflammation in crucian carp. Intestinal inflammation was induced by intrarectal admin-istration of a 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution. The fish samples were fed with different diets for 14 days. The disease activity index (DAI), which included, fish swimming, food intake, anal inflammation, body surface, and ascites was determined daily. Intestine segments were stained with haematoxylin and eosin (H. E.) for histopathological analysis. The expression of cytokines, including interleukin-1 beta (IL-1 beta), interleukin-8 (IL -8), tumor necrosis factor alpha (TNF-alpha), and myeloperoxidase (MPO) in crucian carp were determined. In TNBS-induced groups, the DAI scores were dramatically increased compared to the control group. The histopatho-logical analysis showed that the damage of the fish intestine after the injection of TNBS. The relative expression levels of pro-inflammation cytokines (TNF-alpha, IL-1 beta, IL-8, MPO) were significantly increased compared to the control group on day 1. In the TNBS-induced group feed with a diet supplemented with bioactive peptide, the symptoms of intestinal inflammation were relieved on day 3 and the mRNA expression levels of pro -inflammation cytokines (TNF-alpha, IL-1 beta, IL-8, MPO) were reduced compared to day 1. On day 7, the fish sam-ples enrofloxacin group and bioactive peptide group were recovered from TNBS-induced intestinal inflammation. This study showed that the fish diet supplemented with bioactive peptide could help to prevent and recover from intestinal inflammation. Thus, the bioactive peptide can be used as a replacement for antibiotics to prevent disease in aquaculture production.