Intestinal Barrier Integrity: The Essential Role of Neuropeptides and Their Implications in the Pathogenesis of Gastrointestinal Diseases

The intestinal barrier relies on tight junctions and proteins including claudins, occludins, and zonula occludens, helping to seal the epithelial cell gaps and hence controlling permeability. When tight junctions are disrupted, intestinal permeability increases, a condition recognised as "leaky gut." This condition is linked to gastrointestinal (GI) disorders including inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). Neuropeptides are crucial in modulating the tight junctions’ integrity within the GI epithelial barrier. This review focuses on neuropeptide Y, vasoactive intestinal peptide, cholecystokinin, and substance P in regulating intestinal barrier integrity. Studies included in this narrative review were selected based on their relevance to the topic, identified through searches in databases such as Google Scholar, PubMed, and Mendeley using relevant keywords. Understanding the mechanisms of these neuropeptides may provide pathophysiological insights and potential treatment strategies for restoring intestinal barrier integrity in GI disorders.