Importance of histamine, glutathione and oxyradicals in modulating gastric haemorrhagic ulcer in septic rats.

1. The ulcerogenesis of gastric haemorrhagic damage during sepsis is unclear. The present study first proposes that gastric haemorrhagic ulcer is modulated by mucosal glutathione, histamine and oxyradicals in lipopolysaccharide (LPS)-induced sepsis in rats. The protective effects of several drugs on the ulcerogenic parameters also were evaluated. 2. Male specific pyrogen-free Wistar rats were deprived of food for 24 h. For the induction of sepsis, intravenous LPS (0, 1, 3 or 10 mg/kg in 1 mL sterilized normal saline) was challenged to rats 12 h after withdrawal of food. Rat stomachs were vagotomized, followed by irrigation for 3 h with normal saline or a physiological acid solution containing 100 mmol/L HCI and 54 mmol/L NaCl. 3. The aggravation of gastric ulcerogenic parameters, such as gastric acid back-diffusion, luminal haemoglobin content, mucosal lipid peroxide production, histamine concentration, as well as lowered concentrations of defensive substances, including mucosal glutathione, were dependent on the doses of LPS used for challenge. A high correlation was observed between mucosal histamine release and lipid peroxide production in LPS rats. 4. The ulcerogenic parameters obtained in LPS (3 mg/kg, i.v.) rats were potently attenuated by diamine oxidase, ketotifen and zinc sulphate. 5. Several oxyradical scavengers, including glutathione, dimethylsulphoxide and allopurinol, also were effective in inhibiting haemorrhagic ulcer. 6. In conclusion, gastric mucosal histamine release and oxyradical generation play pivotal roles in the formation of haemorrhagic ulcers in septic rats.