Effects of Proanthocyanidins on Growth Performance, Intestinal Inflammation and Barrier Function, and Bile Acid Metabolism-Related Genes in Weaned Piglets Challenged with Lipopolysaccharide.

This study aims to investigate the effects of dietary proanthocyanidins (PACs) on growth performance, intestinal inflammation and barrier function, and bile acid metabolism-related genes in weaned piglets challenged with lipopolysaccharide (LPS). A total of 18 21-day-old castrated piglets (7.16 ± 1.66 kg) were randomly assigned to three groups: (1) CON (a basal diet), (2) LPS (a basal diet + LPS), (3) LPS + PAC (a basal diet + LPS + 250 mg/kg PAC), with each group consisting of six replicates of 1 piglet per treatment. The study lasted for 21 days. On the 14th and 21st days of the experiment, piglets in the LPS and LPS + PAC groups received an intraperitoneal injection of 100 µg/kg body weight of LPS, while the piglets in the CON group received an injection of 0.9% normal saline solution. The LPS + PAC group exhibited a significantly higher average daily gain (ADG) than the LPS group (p < 0.05). LPS stimulation resulted in a decreased (p < 0.05) villus height of the jejunum and ileum and an increased number of goblet cells. These effects were alleviated (p < 0.05) in the LPS + PAC group. The LPS + PAC group decreased the level of TNF-α and D-lactate in serum and the gene expression of IL-6 and IL-1β in the ileal tissue, compared with the LPS group, while increasing the gene expression of Occludin and ZO-1 in the ileal tissue (p < 0.05). LPS stimulation down-regulated the expression of genes regulating bile acid synthesis and transport, including hepatic CYP7A1 and ileum ASBT, whereas dietary PAC had no significant effect on the expression of these genes (p > 0.05). Nevertheless, supplementation with PAC significantly increased the expression levels of GLP-2R, GCG, and TGR5 in the ileum of piglets (p < 0.05). Additionally, piglets in the LPS + PAC group exhibited a significant increase in the level of glucagon-like peptide 2 (GLP-2) compared with the LPS group (p < 0.05). PAC generally improves the ADG, intestinal morphology, and intestinal barrier function of piglets by activating TGR5 to stimulate the intestinal secretion of GLP-2.