Gastric ulcer healing in the rat: kinetics and localisation of de novo procollagen synthesis

Abstract

Background and aims—To gain further insight into the role of the extracellular matrix during healing of peptic ulcers, sequential changes of procollagen expression were studied over 30 days of ulcer healing.Materials and methods—Procollagens α1(I), α1(III), and α1(IV) RNA and their polypeptides were assessed in acetic acid induced rat gastric ulcers by in situ hybridisation and immunohistochemistry.Results—Three days after ulcer induction, intense hybridisation signals were obtained with all probes, with procollagen α1(I) showing the highest transcript levels. Procollagen gene expression remained elevated up to day 15, but was reduced to initial low levels on day 30. Immunohistochemical staining documented increased deposition of the three procollagen types parallel to their respective transcript levels, again with type I showing the earliest and the most prominent deposits. The highest procollagen transcript levels were found in the intact submucosa surrounding the ulcer margins, followed by the muscularis propria and the serosa, with the lamina propria exhibiting the lowest transcript levels.Conclusion—The procollagens studied are regulated differentially at the transcriptional and post-transcriptional levels. The early onset and long duration of procollagen expression as well as the involvement of all layers of the gastric wall points to their central structural and functional role in gastric ulcer healing.