RELATIONSHIP BETWEEN GASTRIC MUCOSAL PROSTAGLANDIN LEVELS AND HEALING OF GASTRIC LESIONS IN RATS

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Abstract
1. This study was designed to determine whether or not endogenous prostaglandins (PG) contribute to the healing of gastric ulcers induced by high concentrations of ethanol or water immersion stress. 2. Ethanol‐induced gastric lesions; rats were divided into four groups: (1) the control group: untreated; (2) the indomethacin group: indomethacin (2 mg/kg) was injected intramuscularly (i.m.) once daily until the end of the experiment; (3) the ethanol group: rats were given 1 mL of 50% ethanol intragastrically; (4) the ethanol + indomethacin group: indomethacin (2 mg/kg) was injected (i.m.) once daily from 1 h after administration of 50% ethanol until the end of the experiment. 3. Water immersion stress‐induced gastric lesions; rats were divided into three groups: (1) control group: untreated; (2) stress group: rats were placed in a stress cage and immersed into a water bath (23°C) for 6 h; (3) stress + indomethacin group: indomethacin (2 mg/kg) was injected (i.m.) once daily for 3 consecutive days immediately after stress treatment or from 3 days after stress treatment until the end of the experiment. 4. Immediately after observation of the lesions, the fundic mucosal layer was separated from the muscle layer and mucosal PG levels were measured by high performance liquid chromatography in each group. 5. Indomethacin did not inhibit ulcer healing until 48 h after administration in the ethanol experiment, and until 3 days after administration in the water immersion experiment. In contrast, indomethacin inhibited ulcer healing thereafter in each experiment respectively. 6. Four kinds of PG, that is 6‐keto‐PGF1α PGF2α, PGE2 and PGD2 were detected in gastric mucosa. Indomethacin inhibited the recovery of PG levels, and significantly low PG levels were observed after indomethacin treatment. 7. It was noted from the effect of indomethacin that there are at least two phases of healing in gastric ulcers (i.e. the early phase and the late phase), and that PG might be linked with the late phase of ulcer healing.