HELICOBACTER-PYLORI LIPOPOLYSACCHARIDE INHIBITS ACID-SECRETION IN PYLORUS-LIGATED CONSCIOUS RATS

To examine the effect of Helicobacter pylori lipopolysaccharide on gas tric secretion, the present study was carried out using pylorus ligate d conscious rats, Intraperitoneal administration of Helicobacter pylor i lipopolysaccharide significantly inhibited gastric acid secretion (4 hr) in a dose-dependent manner (0.033-1.0 mg/rat), The Helicobacter p ylori lipopolysaccharide (1 mg/rat)-induced acid inhibition was still observed 8 hr after injection. Gastric acid secretion (4 hr) was compa red in the rats that had received intraperitoneal administration of 1 mg/rat dose of Helicobacter pylori lipopolysaccharide or saline alone 24 hr before. There was no significant difference in gastric acid secr etion between the saline- and H. pylori lipopolysaccharide-treated rat s, These results suggest for the first time that H. pylori lipopolysac charide may inhibit acid production, and this acid inhibition may be l ong-lasting, It is also demonstrated that this anti-secretory action o f H. pylori lipopolysaccharide has a reversible effect on gastric secr etion. All these results suggest that H. pylori lipopolysaccharide mig ht be involved in the low acid secretory function seen in patients wit h acute H. pylori infection. (C) 1997 Academic Press.