α-Glycerol Monolaurate Promotes Tight Junction Assembly and Enhances Epithelial Barrier Function in IPEC-J2 Cells and Partridge Chicks

This study investigated the role and mechanism of α-glycerol monolaurate (α-GML), a Food and Drug Administration–approved natural emulsifier, in enhancing tight junction (TJ) assembly and intestinal barrier function. In vitro experiments showed that α-GML significantly increased the gene and protein levels of TJ-related occludin (OCLN) and zonula occluden-1 (ZO-1), increased ZO-1 distribution in the cell membrane, and reduced paracellular permeability in porcine jejunum epithelial cells (IPEC-J2). These findings indicated that α-GML enhanced intestinal barrier function by promoting TJ protein expression and assembly. Compared with the α-GML group, TJ protein expression and assembly and AMP-activated protein kinase (AMPK) phosphorylation were significantly downregulated in cotreatment groups receiving α-GML along with a calcium-sensing receptor antagonist or a phospholipase C inhibitor. Notably, the groups treated with α-GML and inositol 1,4,5-trisphosphate receptor inhibitor showed a significant decrease in TJ assembly and AMPK phosphorylation, with no significant difference in the TJ protein expression levels. In vivo experiments demonstrated that dietary α-GML significantly upregulated TJ levels and AMPK phosphorylation in the jejunum of partridge chicks. In conclusion, α-GML may upregulate intestinal epithelial TJ assembly via AMPK activation and promote intestinal barrier development in young animals to maintain intestinal health.