AIM: To evaluate the effect of acute stress, hydrochloric acid, ethanol, aspirin, and prednisolone on the intercellular spaces of the esophageal epithelium. METHODS: Part I, male Sprague-Dawley rats were randomly divided into eight groups and treated with the damaging or control factors. The esophagus of each rat was macroscopically inspected. Histological changes in mucosal biopsies were examined by light microscopy, and the widths of intercellular spaces were determined by transmission electron microscopy (TEM). Part II, in part I, we found that acute stress and aspirin induced dilated intercellular spaces (DIS) of the esophageal epithelium. Therefore, the effect of acid suppression pretreatment with esomeprazole on esophageal epithelial DIS induced by water immersion and restraint stress (WRS) and aspirin was further investigated to determine the association of DIS with acid reflux. After administration of 0.9% sodium chloride solution or esomeprazole solution orally for five days, rats underwent WRS or intragastric administration of aspirin solution. Esophageal epithelial intercellular spaces were investigated by TEM. RESULTS: (1) The five damaging factors produced no lesions or inflammation in esophageal mucosa of rats under either gross or routine histological inspections. Esophageal epithelial intercellular space diameters in stress and aspirin groups were significantly greater, nearly three or two-fold respectively, than those in their corresponding control groups (stress model: 0.38 + or - 0.05 microm vs 0.13 + or - 0.02 microm, P < 0.01; aspirin model: 0.32 + or - 0.12 microm vs 0.19 + or - 0.05 microm, P < 0.01). Neither intragastric administration of hydrochloric acid or ethanol, nor hypodermic injection of prednisolone produced DIS compared with their corresponding control groups (hydrochloric acid model: 0.24 + or - 0.03 microm vs 0.19 + or - 0.05 microm, P > 0.05; ethanol model: 0.25 + or - 0.10 microm vs 0.19 + or - 0.05 microm, P > 0.05; prednisolone model: 0.20 + or - 0.03 microm vs 0.14 + or - 0.03 microm, P > 0.05); and (2) No significant difference in the intercellular space diameters was observed between the group pretreated with esomeprazole and the control group, in both the stress and aspirin models (stress model: 0.35 + or - 0.05 microm vs 0.37 + or - 0.05 microm, P > 0.05; aspirin model: 0.24 + or - 0.02 microm vs 0.27 + or - 0.03 microm, P > 0.05). CONCLUSION: Acute stress and aspirin can induce DIS of the esophageal epithelium in rats, and it is not correlated with acid reflux.