ABDOMINAL SURGERY-INDUCED INHIBITION OF GASTRIC-EMPTYING IS MEDIATED IN PART BY INTERLEUKIN-1-BETA

The role of interleukin-1 beta (IL-1 beta) in abdominal surgery-induce d inhibition of gastric emptying was investigated. Abdominal surgery w as performed under halothane anesthesia, and 5 min later, the 20-min r ate of gastric emptying was measured by the phenol red method in consc ious animals. In nonoperated animals, intravenous IL-1 beta dose depen dently decreased gastric emptying from 55.1 +/- 1.7% in controls to 8. 0 +/- 3.5% (P < 0.05) after treatment with 1 mu g IL-1 beta. Prior adm inistration of IL-1 beta receptor antagonist (IL-1 beta ra; 200 mu g) completely abolished the inhibitory effects of IL-1 beta. Surgery inhi bited gastric emptying by 83.4% compared with rats receiving anesthesi a alone. IL-1 beta ra (200 mu g) reversed the inhibition of gastric em ptying by 34.8% (P < 0.05) in the early (30 min) postoperative period and by 32.3% (P < 0.05) in the late (120 min) postoperative period. Us e of calcitonin gene-related peptide-(8-37) [CGRP-(8-37)] in combinati on with IL-1 beta ra in operated animals resulted in no further revers al in the inhibition of gastric emptying: CGRP-(8-37)-treated animals = 42.1 +/- 4.1%; CGRP-(8-37) + IL-1 beta ra = 38.0 +/- 4.4% (not signi ficant). Moreover, in nonoperated animals, CGRP(8-37) completely aboli shed the effects of intravenous IL-1 beta on gastric emptying: IL-1 be ta-treated animals = 11.1 +/- 2.0%; IL-1 beta +/- CGRP-(8-37) = 40.6 /- 6.4% (P < 0.05). These results suggest that IL-1 beta is mediating part of the gastric ileus observed after abdominal surgery through the release of CGRP from the visceral afferents.