Extract

Our previous studies on the protein expression of claudins in an experimental model of rat reflux esophagitis (RE) suggested that claudin-3 could be a key TJ barrier protein. However, the structure of TJs in the esophagus of normal rats and the structural changes that occur in association with RE have not been fully clarified. Therefore, extensive morphological analyses of the rat esophageal epithelium under normal conditions and in chronic RE were carried out using electron microscopy of ultra-thin sections and freeze-fracture replicas in addition to immunoelectron microscopy of claudin-3 using ultra-thin cryosections and SDS-digested freeze-fracture replicas. To obtain flat replicas of the esophageal mucosa, we applied the grid-mapped freeze-fracture technique. TJ structures only in the stratum granulosum (SG) of the esophageal epithelia in control rats, and the number of TJ structures seemed to be decreased in the RE model. Most of the TJs were composed of only one “kissing point”. Freeze-fracture electron microscopy did not allow identification of typical TJ strands, suggesting that TJs in the rat esophageal mucosa were not well-developed. Immunoelectron microscopy confirmed our previous immunohistochemical results indicating that claudin-3 was located on the surface of esophageal epithelial cells in control rats and that the immunoreactivity decreased in the RE group. However, claudin-3 was diffusely localized on the plasma membrane and not concentrated on the TJ structures. These results indicate that claudin-3 is not directly involved in the composition of the TJ structure.

You do not currently have access to this article.