Role of leukotrienes in hydrochloric acid-induced gastric lesions in rats.

This study was designed to clarify the role of leukotrienes (LTs) in 0.6 N hydrochloric acid (HCl)-induced gastric lesions. In rats given 1 ml of 0.6 N HCl intragastrically, severe hemorrhagic lesions were observed in the gastric corpus mucosa 15 min, and 1, 3, and 5 hr after HCl administration. In the control rats treated with physiological saline, LTs in gastric mucosa were not observed throughout the experiments. Peptide LT contents (sum of LTC4 and LTD4) after 1 or 3 hr were increased to 13.2 +/- 2.9 ng/g tissue and 6.3 +/- 1.9, respectively, although peptide-LTs were not observed 15 min and 5 hr after HCl administration. Premedication with AA-861, a lipoxygenase inhibitor, decreased dose-dependently peptide LT contents 1 hr after HCl administration. Furthermore, gastric lesions caused by 0.6 N HCl were significantly prevented by 300 mg/kg of AA-861 3 hr after HCl administration, although the dose of AA-861 did not significantly prevent gastric lesions 1 hr after HCl administration. Administration of YM-638, a peptide LT antagonist, showed similar protective effects to AA-861 except inhibition of increase in LT levels after HCl administration. These results suggest that peptide LTs contribute to persistence of gastric lesions, although they might not participate in the onset of 0.6 N HCl-induced gastric lesions.