Morphology and Glycoconjugate Content of Opossum Esophageal Epithelium and Glands: Regional Heterogeneity and Effects of Acid-Induced Mucosal Injury and Recovery

Abstract

This study examined the regional heterogeneity and site-specific changes in histology and glycoconjugate content following the induction of esophagitis and after recovery in an established animal model. Esophageal samples were excised from five sites in anesthetized opossums 24 hr after 3 consecutive days of 45-min perfusion with saline or 100 mM HCl or 1 week after acid in recovery animals. Controls exhibited significant regional differences in epithelial thickness, gland volume, glycoconjugate composition, and mast cell numbers. Acid perfusion induced erosive esophagitis and significant epithelial denudation throughout the distal 7 cm, combined with significant site-specific increases in gland lumen volume, decreases in mast cell numbers, and changes in glycoconjugate content. No differences from controls were noted in recovery animals, except for a significant increase in epithelial thickness and change in glycoconjugate content in the distal 2 cm. The results of this study highlight the impact of acid exposure on these structural defenses, but further investigation is required to explore the importance of these acid-induced changes in the pathogenesis of reflux esophagitis.

Association of erosive esophagitis withHelicobacter pylorieradication: a role of salivary bicarbonate and glycoprotein secretion

“…It is well known that the protective potential of saliva within the esophageal lumen is enhanced by the secretion of esophageal submucosal mucus glands. 3,28 The salivary and esophageal secretions act in line to counteract the damage which might be caused by the endogenous and exogenous factors. In patients with reflux esophagitis, the secretion of protective factors of the esophageal submucosal mucous glands is diminished.…”

Direct Evidence of Mast Cell Participation in Acute Acid‐induced Esophageal Inflammation in Mice

“…Alterations in mast cell numbers have been reported in association with acid‐induced esophageal injury (5,9). We found no change in the number of mast cells at sites of experimental esophagitis.…”

“…We found no change in the number of mast cells at sites of experimental esophagitis. White et al (5) reported a decrease in the number of tissue mast cells associated with acute acid injury to the esophagus of the opossum. One explanation for this difference is in the method used to fix and examine tissues.…”

“…One explanation for this difference is in the method used to fix and examine tissues. In the study by White, Carnoy fixative was used, with paraffin embedding, sectioned at 6‐μm thickness and examined under ×40 magnification (5). This method can underestimate the number of mast cells because it may be difficult to identify mast cells that have undergone extensive degranulation.…”

“…Kim et al (4) demonstrated that hydrochloric acid can cause mast cell degranulation and histamine release in vitro. In opossums, acid‐induced injury to the esophagus is associated with a decrease in mast cell numbers (5), along with evidence of mast cell degranulation (6), and mast cell mediators have been implicated in esophageal shortening and hiatal hernia formation in this experimental model (7).…”