Dietary sanguinarine ameliorates growth impairment and intestinal dysfunction in Ctenopharyngodon idellus fed a high cottonseed meal diet

High cottonseed meal diets can reduce the growth and cause intestinal damage of aquatic animals. Sanguinarine is a plant alkaloid with demonstrated anti-inflammatory. Howerve, its role in the negative effects caused the high cottonseed meal diet is unclear. Herein, an eight-week feeding trial was conducted to evaluate the effects of sanguinarine supplementation in a high cottonseed meal diet on the growth and intestinal health (such as inflammation, physical barrier, oxidative stress, and microbiota of Ctenopharyngodon idellus, providing a theoretical basis for the application of sanguinarine in cottonseed meal diets. A basal diet of 0% cottonseed meal was designated as the control diet (CON). Diets (44% cottonseed meal) supplemented with four sanguinarine (0, 300, 600, and 1200 μg/kg; designated as the CM, CMLS, CMMS, and CMHS, respectively) were prepared. There were 3 replicates per group and 50 fish per replicate. One-way ANOVA and Duncan's multiple comparisons of the means were used in this experiment. The results showed that feeding grass carp with CM obviously reduced the growth, impaired the intestinal physical and immune barrier function, and disrupted the microbiota balance of the intestine. Compared with the CM group, supplemented sanguinarine markedly improved the growth performance, serum AKP, C3, and IgM levels of grass carp, and enhanced intestinal antioxidant capacity ( gpx1, cat, and gsto expression levels obviously up-regulated and ROS and MDA contents reduced). Sanguinarine observably down-regulated the expression levels of il-1β, il-8, il-6, and tnf-α and up-regulated the expression levels of il-10, il-15, and tgf-β1 by inhibiting NF-κB signaling molecules, thereby alleviating intestinal inflammation caused by a CM diet. Additionally, sanguinarine observably down-regulated claudin-12 and claudin-15 gene expression and up-regulated zo-1 and occludin gene expression by inhibiting MLCK signaling molecules. Besides, compared with the CM group, the α-diversity indices and abundances of Proteobacteria, Actinobacteria, and Planctomycetes in the CMMS group were markedly reduced, while the abundance of Firmicutes was the opposite. In conclusion, the CM diet negatively impacted grass carp, and supplemented sanguinarine can improve growth, enhance intestinal antioxidant ability, alleviate intestinal barrier damage, and ameliorate intestinal microbiota homeostasis.