Thereafter, a previous study observed that the colon tissue of the rat model of PD displayed significant changes, including inflammatory infiltration, intestinal barrier injury (reduced claudin-1 and transmembrane 16A/anoctamin 1 expressed by epithelial cells and a compensatory increase of mucin and S100-positive glial cells), and enhanced transmural deposition of collagen fibers (49). This evidence concerns the gene CLDN1 and Parkinson disease.