Dietary supplementation of Lycium barbarum polysaccharides alleviates soybean meal-induced enteritis in spotted sea bass Lateolabrax maculatus

The aim of this experiment was to investigate the effect of <i>Lycium barbarum</i> polysaccharides (LBP) on alleviating soybean meal-induced enteritis (SBMIE) in spotted sea bass <i>Lateolabrax maculatus</i>. The diet with 44% fishmeal (FM) content was used as a blank control, and soybean meal (SM) was used to replace 50% FM as an experimental control to induce enteritis. Then, on the basis of experimental control, 0.10%, 0.15%, and 0.20% LBP were added as experimental diets. A total of 225 spotted sea bass (44.52 ± 0.24 g) were randomly divided into 5 groups and fed the corresponding diets for 52 d. The results showed that 0.15% LBP decreased serum D-lactic acid (D-LA) content and diamine oxidase (DAO) activity (<i>P</i> < 0.05). In addition, in all LBP supplementation groups, the intestinal tissue morphology was significantly improved (<i>P</i> < 0.05); the intestinal microbial structure gradually recovered to a level close to that without adding SM; and the microbial species richness and diversity were significantly increased (<i>P</i> < 0.05). Through transcriptomic and metabolomic analysis, it was found that the expression of proinflammatory factors such as interleukin-1β (<i>IL-1β</i>), interleukin-12 (<i>IL-12</i>), nuclear factor kappa B subunit 2 (<i>NF-κB2</i>), and Toll-like receptor 2 (<i>TLR2</i>) were significantly down-regulated in the mitogen-activated protein kinase (MAPK) and Toll-like receptor signaling pathways (<i>P</i> < 0.05), and the important tight junction protein gene <i>Occludin</i> was up-regulated (<i>P</i> < 0.05). In addition, LBP down-regulated saponin metabolites and up-regulated amino acid metabolites (<i>P</i> < 0.05). In conclusion, LBP demonstrated a significant alleviating effect on SBMIE of spotted sea bass <i>L. maculatus.</i>