The interrelationship between salivary epidermal growth factor and the functional integrity of the esophageal mucosal barrier in the rat

Abstract

The role of salivary epidermal growth factor (sEGF) in the maintenance of the esophageal mucosal mucus coat and its permselective properties was investigated for this study. Eighteen Sprague-Dawley male rats underwent sialoadenectomy (SAD), while 18 others with sham operation served as a control. Nine SAD rats in each group received EGF in a dose of 15 micrograms/kg/d for five consecutive days prior to sacrifice. Esophageal mucosa dissected from the muscle layer was placed in the central port of a specially designed permeability chamber filled on both sides with equimolar solutions of NaCl or HCl (0.155 M). The rate of hydrogen ion diffusion from the mucosal to the serosal side was estimated by continuous recording of pH in the NaCl compartment. In addition, the mucosal mucus coat was evaluated by Alcian blue uptake methodology. SAD led to a 108% increase in the rate of permeability of the esophageal mucosa to hydrogen ion. Simultaneously, an 83% decrease in the mucus content on the surface of the esophageal mucosa was observed. A five-day supplementation of EGF substantially improved the permeability of esophageal mucosa (67%) and the mucous layer of esophagus (41%). sEGF seems to play an important physiological role in the maintenance of the functional integrity of the esophageal mucosa.