Studies on the gastroulcerogenic effects of pylorus ligation, hypothermic restraint stress, aspirin, indomethacin and reserpine in morphine dependent rats.

The gastric mucosal damage induced by pylorus ligation for 6 h, hypothermic restraint stress, aspirin, indomethacin and reserpine was studied in morphine dependent rats. Morphine tolerance and dependence were produced by administering the gradually increasing concentrations of morphine sulphate in drinking water for 21-24 days. The tolerance and dependence produced by morphine were confirmed by a decreased analgesic response to morphine in the hot plate test and by producing a naloxone precipitated withdrawal syndrome respectively. The intensity of gastric mucosal damage induced by pylorus ligation, aspirin and indomethacin was significantly higher in morphine dependent rats than that observed in the naive animals. Studies on the gastric secretion did not reveal any significant change in the volume of gastric secretion, titrable acidity and gastric output of 6 h pylorus ligated rats. The average lesion scores in the reserpine treated and hypothermic restraint stressed rats were not significantly different from those obtained in the naive animals. Further studies are required to establish the exact mechanisms underlying these observations.