The Effects of Naringin on Growth Performance, Antioxidant Function, Intestinal Barrier and Immune Response in Broilers Challenged with Lipopolysaccharide

This study aimed to investigate the effects of naringin (NG) on growth performance, antioxidant status, intestinal barrier function, and immune stress in broilers challenged with lipopolysaccharide (LPS). A total of 144 one-day-old Arbor Acres broilers were randomly allocated into 2 treatment groups, with six replicates per group and 12 birds per replicate. The groups consisted of a control group (fed a basal diet) and a NG group (fed the basal diet supplemented with 200 mg/kg NG). The trial lasted 35 days, and body weight was recorded on the days 21 and 35 to evaluat growth performance. On day 21, two birds per replicate were intraperitoneally injected with 0.5 mg/kg body weight (BW) LPS, while another two birds received an equal volume of saline. Chickens were slaughtered 3 hours post-injection for sample collection. Dietary NG supplementation had no significant effect on the growth performance (p > 0.05). However, NG significantly mitigated the LPS-induced increases in plasma alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels, while attenuating the LPS-induced decreases in plasma total bilirubin (TB), triglyceride (TG), total cholesterol (TC), and low-density lipoprotein (LDL) levels (p < 0.05). NG supplementation significantly increased hepatic glutathione peroxidase (GSH-Px) activity, duodenal and ileal catalase (CAT) activity, and ileal GSH-Px activity. while reducing malondialdehyde (MDA) levels in the liver, duodenum, jejunum, and ileum, as well as hydrogen peroxide (H2O2) levels in the jejunum and ileum (p < 0.05). Dietary NG supplementation significantly upregulated the relative mRNA expression of Toll-like receptor 4 (TLR4) and interferon-gamma (IFN-γ) in the liver (p < 0.05) and attenuated the LPS-induced upregulation of tumor necrosis factor-alpha (TNF-α) mRNA expression in the jejunum (p < 0.05). NG reduced serum diamine oxidase (DAO) levels (p < 0.05), increased villus height in the duodenum and jejunum (p < 0.05), and increased the villus height to crypt depth (VH/CD) ratio in the jejunum (p < 0.05). Moreover, NG significantly upregulated the relative mRNA expression of zonula occludens-1 (ZO-1) and occludin in the duodenum, while significantly downregulating the relative expression of mucin-2 in the duodenum and ileum (p < 0.05). NG further reduced mucin-2 expression in the jejunum and mitigated the LPS-induced downregulation of ZO-1 in the ileum (p < 0.05). In addition, NG significantly upregulated the expression of X-linked inhibitor of apoptosis protein (XIAP) and B-cell lymphoma 2 (Bcl-2) and downregulated the expression of matrix metalloproteinase-13 (MMP-13) in the liver of LPS-challenged broilers (p < 0.05). conclusion,, dietary NG supplementation alleviated LPS-induced intestinal and hepatic injury in broilers. NG attenuated the adverse effects of LPS challenge on the intestinal barrier function and enhanced antioxidant capacity in broilers by modulating intestinal tight junction expression and .antioxidant enzyme activity, providing evidence for its potential application in broiler production.