The effect of morphine on development of ulcer lesions of the rats exposed to indomethacin induced stress

Oxidative stress plays an important role in development of ulcer lessions of the rats exposed to indomethacin induced stress. It has been suggested that endogenous opioids releassed during the stress may attenuate gastric ulcer lesions. The aim of this study was to investigate effects of morpine on development of ulcer lessions, pathohistological alterations and antioxidative status in stomach of the rats exposed to indomethacin induced stress. Research was performed on adult, male Wistar rats weighting 200-230 g. Indomethacin stress was induced by intragastric administration of indomethacin at a dose of 20 mg/kg b.w. 6 hours before sacrificing. Morphine was applied intraperitoneally, in the doses of 10 mg/kg b.w. 15 minutes before indomethacin induced stress. The size of lesions in the form of petechiae and erosion, is expressed as the total surface of changes (mm2), i.e. ulcer index (UI). The pathohistological samples were analyzed by Leica DML S2 light microscope, and specific changes were photodocumented with Canon Power Shot S70 digital camera. In the homogenate of the stomach, the activity of catalase (CAT), glutathione peroxidase (GSHPx), glutathione reductase (GR) and xanthine oxidase (XOD) were measured, as well as the reduced glutathione content (GSH) and the lipid peroxidation intensity (Lpx). Morphine significantly reduced the ulcer index (UI) in animals exposed to indomethacin stress and the presence of large amounts of mucus in the stomach mucosal was established histopathologically. The use of morphine in the pretreatmant of indomethacin induced stress statistically significantly reduced the activity of all enzymes in the stomach compared to the control group, and this activity of catalase (CAT), glutathione peroxidase (GSHPx) and glutathione reductase (GR ), xanthine oxidase (XOD),as well as the lipid peroxidation intensity (Lpx), while the reduced glutathione content remained unchanged. Gastroprotective morphine activity in animals exposed to indomethacin induced stress is most likely a consequence of the strengthening of cytoprotective mechanisms rather than antioxidant action.