Effect of Dietary Histamine on Intestinal Morphology, Inflammatory Status, and Gut Microbiota in Yellow Catfish (pelteobagrus Fulvidraco).

The toxic effect of dietary histamine on the intestine of aquatic animals has been demonstrated, but reports on the morphological observation of the intestine are limited. Thus, a feeding trial was conducted to determine the effect of dietary histamine on intestinal histology, inflammatory status and gut microbiota of yellow catfish (Pelteobagrus fulvidraco). Here, we showed that histamine-rich diets caused severe abnormality and damage to the intestine, including a decreased villi length and reduced villi number. In addition, the quantitative real-time PCR (qRT-PCR) demonstrates that histamine-rich diets increased the expression of pro-inflammatory genes (Tnfα, Il1β, and Il8) and decreased the expression of an anti-inflammatory gene (Il10). Furthermore, the alpha-diversity (observed OTUs, Chao1, Shannon and Simpson) and beta-diversity (non-metric multidimensional scaling, with the stress value of 0.17) demonstrated that histamine-rich diets caused alterations in gut microbiota composition and diversity. Co-occurrence networks analysis of the gut microbiota community showed that the histamine influenced the number and the relationship between bacteria species in the phyla of Acidobacteria, Proteobacteria, and Bacteroidetes, which caused the instability of the intestinal microbiota community. Additionally, random forest selected six bacterial species as the biomarkers to separate the three groups, which are Lachnospiraceae Blautia (V520), Bacteroidales S24.7 (V235), Chloroplast Streptophyta (V368), Actinomycetales Streptomycetaceae (V152), Clostridia Clostridiales (V491) and Paraprevotellaceae Prevotella (V245). Finally, Pearson correlation analysis demonstrated that V520, V235, and V491 were negatively correlated with pro-inflammatory factors (Tnfα, Il1β, and Il8) and positively correlated with an anti-inflammatory factor (Il10), which indicated that V520, V235, and V491 might be anti-inflammatory. These findings improved our understanding of the toxic effect of dietary histamine to intestinal histological damage, the induction of mucosa inflammatory status, and the alteration of gut microbiota.