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Pathogenic mechanisms involved in mepirizole-induced duodenal damage in the rat
Abstract:
Mepirizole (60 and 200 mg/kg) administered s.c. induced damage in the surface epithelial cells of the rat proximal duodenum as early as 2 hr after the treatment. 16,16-Dimethyl prostaglandin E2 (dmPGE2, 30 micrograms/kg) administered s.c. significantly protected the duodenal mucosa against mepirizole-induced damage for up to 6 hr. Gastric acid secretion in acute fistula preparations was significantly reduced 1 hr after administration of mepirizole (60 and 200 mg/kg). The secretion reverted to the control level 2 hr later. In the 60 mg/kg-treated group, however, there was a significant increase in the acid output for up to 6 hr. Duodenal HCO3- secretion, stimulated with 10 mM HCl was significantly inhibited with mepirizole (60 and 200 mg/kg). Mepirizole (60 and 200 mg/kg) significantly increased the amount of acid in the duodenum for 2 to 6 hr after the treatment. dmPGE2 (30 micrograms/kg) significantly inhibited gastric acid secretion, stimulated duodenal HCO3- secretion, and reduced the increased amount of acid in the duodenum in response to mepirizole. Endogenous prostaglandin E2 and 6-keto prostaglandin F1 alpha in the duodenal mucosa were significantly reduced by mepirizole (200 mg/kg) 1 to 2 hr later. Mepirizole-induced duodenal damage appears to be caused by the increased amount of acid in the duodenum.
Insights
Mepirizole causes duodenal damage by increasing acid. 16,16-Dimethyl prostaglandin E2 (dmPGE2) protects the duodenum by reducing acid and increasing bicarbonate secretion, counteracting mepirizole's effects.
Area of Science:
- Gastroenterology
- Pharmacology
- Cell Biology
Background:
- Mepirizole administration causes damage to the surface epithelial cells of the rat proximal duodenum.
- Prostaglandins play a crucial role in maintaining mucosal integrity and regulating gastric and duodenal secretions.
Purpose of the Study:
- To investigate the protective effects of 16,16-Dimethyl prostaglandin E2 (dmPGE2) against mepirizole-induced duodenal damage.
- To elucidate the mechanisms underlying mepirizole-induced duodenal damage, focusing on acid and bicarbonate secretion.
Main Methods:
- Rats were administered mepirizole (60 and 200 mg/kg) subcutaneously to induce duodenal damage.
- 16,16-Dimethyl prostaglandin E2 (dmPGE2, 30 micrograms/kg) was administered to assess its protective effects.
- Gastric acid secretion was measured in acute fistula preparations.
- Duodenal bicarbonate (HCO3-) secretion was stimulated with 10 mM HCl.
- Levels of endogenous prostaglandin E2 and 6-keto prostaglandin F1 alpha in the duodenal mucosa were measured.
Main Results:
- Mepirizole induced duodenal epithelial cell damage and increased duodenal acid levels.
- dmPGE2 significantly protected the duodenal mucosa against mepirizole-induced damage.
- Mepirizole inhibited duodenal HCO3- secretion, while dmPGE2 stimulated it.
- Mepirizole reduced endogenous prostaglandins in the duodenal mucosa, suggesting a role in the damage mechanism.
Conclusions:
- Mepirizole-induced duodenal damage is primarily caused by an increased amount of acid in the duodenum.
- dmPGE2 exerts a protective effect by inhibiting gastric acid secretion, stimulating duodenal HCO3- secretion, and reducing duodenal acid levels.