IL-1 Receptor Antagonist Blocks the Lipopolysaccharide-Induced Inhibition of Gastric Motility in Freely Moving Conscious Rats

BACKGROUND AND AIMS: Endotoxin/lipopolysaccharide (LPS) alters gastrointestinal functions. However, little is known as to whether LPS could change gastric antral contractility in freely moving conscious animals. We tried to clarify this problem and the associated mechanisms. METHODS: In this study, we recorded intraluminal gastric pressure waves in freely moving conscious rats by manometric catheter located in the antrum. Area under the manometric trace was evaluated as motor index (MI). RESULTS: Intraperitoneal injection of LPS at doses of 0.2 mg/kg or more significantly inhibited MI. The inhibition started immediately after the administration of LPS and lasted over 1 h. Intraperitoneal injection of IL-1β potently decreased MI while neither IL-6 nor TNF-α inhibited gastric motility, suggesting IL-1β specifically reduced gastric motility. Next, we examined the hypothesis that endogenous IL-1 mediates the LPS-induced inhibition of gastric motility. To address the speculation, an IL-1 receptor antagonist (IL-1Ra) was used to block IL-1 signaling. Pretreatment with IL-1Ra at a dose of 20 mg/kg significantly blocked the inhibition of gastric contractility by LPS at a dose of 0.2 mg/kg. CONCLUSIONS: These results suggest for the first time that LPS or IL-1β is capable of inhibiting gastric motility in conscious rats and that endogenously released IL-1 may mediate the LPS-evoked inhibition of gastric antral motility. This evidence also led us to speculate that IL-1Ra may be a therapeutic tool for patients with disturbed gastrointestinal functions under septic conditions.