Chronic omeprazole treatment increases duodenal susceptibility to ethanol injury in rats

Mucoadhesive effect of Curcuma longa extract and curcumin decreases the ranitidine effect, but not bismuth subsalicylate on ethanol-induced ulcer model

The study of pharmacological interactions between herbal remedies and conventional drugs is important because consuming traditional herbal remedies as supplements or alternative medicine is fairly common and their concomitant administration with prescribed drugs could either have a favorable or unfavorable effect. Therefore, this work aims to determine the pharmacological interactions of a turmeric acetone extract (TAE) and its main metabolite (curcumin) with common anti-ulcer drugs (ranitidine and bismuth subsalicylate), using an ethanol-induced ulcer model in Wistar rats. The analysis of the interactions was carried out via the Combination Index-Isobologram Equation method. The combination index (CI) calculated at 0.5 of the affected fraction (fa) indicated that the TAE or curcumin in combination with ranitidine had a subadditive interaction. The results suggest that this antagonistic mechanism is associated to the mucoadhesion of curcumin and the TAE, determined by rheological measurements. Contrastingly, both the TAE and curcumin combined with bismuth subsalicylate had an additive relationship, which means that there is no pharmacological interaction. This agrees with the normalized isobolograms obtained for each combination. The results of this study suggest that mucoadhesion of curcumin and the TAE could interfere in the effectiveness of ranitidine, and even other drugs.

Role of proton pump inhibitor on esophageal carcinogenesis and pancreatic acinar cell metaplasia development: an experimental in vivo study

Chronic gastro-duodenal reflux in the esophagus is a major risk for intestinal metaplasia and Barrett’s adenocarcinoma. A role for chronic use of proton pump inhibitor (PPI) in the increased incidence of esophageal adenocarcinoma in Western countries has been previously suggested. The aim of this work was to study the effect of chronic administration of omeprazole (a proton pump inhibitor) per os in a model of reflux induced esophageal carcinogenesis. One week after esophago-gastro-jejunostomy, 115 Sprague-Dawley rats were randomized to receive 10 mg/Kg per day of omeprazole or placebo, 5 days per week. The esophago-gastric specimens were collected 28±2 weeks after randomization and analyzed in a blinded fashion. Mortality and esophageal metaplasia rates did not differ between the two groups (p = 0.99 for mortality, p = 0.36 for intestinal metaplasia and p = 0.66 for multi-layered epithelium). Gastric pancreatic acinar cell metaplasia (PACM) was more frequently observed in PPI-treated rats (p = 0.003). Severe ulcer lesions significantly prevailed in the placebo group (p = 0.03). Locally invasive esophageal epithelial neoplasia were observed in 23/39 PPI-treated versus 14/42 placebo-animals (p = 0.03). In conclusion, chronic omeprazole treatment improved the healing of esophageal ulcerative lesions. Locally invasive neoplastic lesions and PACM prevailed among PPI-treated animals. However, neither an effect on the overall mortality nor on the incidence of pre-neoplastic lesions was observed in this work.

Factors influencing intercellular spaces in the rat esophageal epithelium

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 ± 0.05 μm vs 0.13 ± 0.02 μm, P < 0.01; aspirin model: 0.32 ± 0.12 μm vs 0.19 ± 0.05 μm, 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 ± 0.03 μm vs 0.19 ± 0.05 μm, P > 0.05; ethanol model: 0.25 ± 0.10 μm vs 0.19 ± 0.05 μm, P > 0.05; prednisolone model: 0.20 ± 0.03 μm vs 0.14 ± 0.03 μm, 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 ± 0.05 μm vs 0.37 ± 0.05 μm, P > 0.05; aspirin model: 0.24 ± 0.02 μm vs 0.27 ± 0.03 μm, 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.

Effect of difluoromethylornithine (DFMO) on NSAID-induced intestinal injury in rats

Combination therapy with difluoromethylornithine (DFMO) and a nonsteroidal antiinflammatory drug (NSAID) has been proposed for the chemoprevention of colonic neoplasia. The purpose of this study was to examine whether DFMO would affect NSAID-mediated intestinal injury. Male Sprague-Dawley rats were gavaged with 20 mg/kg of indomethacin, after seven days of exposure to drinking water with or without 2% DFMO. The rats were killed 24 or 48 hr later, and the small intestine removed for macroscopic and microscopic quantitation of intestinal injury by computerized image analysis. Seven days of DFMO alone had no effect on overall mucosal thickness, but did increase the depth of proximal intestinal crypts. Forty-eight hours after indomethacin, DFMO treatment decreased the number of indomethacin-induced ulcers and percent of the surface area ulcerated. However, DFMO also decreased the mucosal thickness, villus height, and crypt depth in indomethacin-treated rats. Thus although DFMO decreases macroscopic intestinal ulceration by indomethacin, the reduction in villus and crypt height suggests that it also impairs the mucosa's ability to recover from microscopic indomethacin-induced damage. This study shows DFMO does impact NSAID-mediated intestinal injury and therefore human trials with combinations of DFMO and NSAIDs should include monitoring for small intestinal injury.

Importance of gastric acid in gastric ulcer formation in rabbits with antibody-induced prostaglandin deficiency

The role of gastric acid in the development of gastroduodenal ulcers in prostaglandin-deficient conditions is unclear. In the current study, the effect of the proton pump inhibitor omeprazole on the formation of gastric ulcers was examined in a previously validated rabbit model of antibody-induced prostaglandin deficiency. Intragastric administration of 20 mg/kg omeprazole every 12 hours caused a profound suppression of gastric acidity (i.e., pH above 5 continuously). This same dose of omeprazole significantly reduced gastric ulcer formation induced by passive immunization with 6-keto-prostaglandin F1 alpha antibodies. It is concluded from these observations that gastric acid plays a critical role in the formation of gastric ulcers in rabbits with antibody-induced prostaglandin deficiency.