ROLE OF SPINAL AFFERENTS AND CALCITONIN-GENE-RELATED PEPTIDE IN THE POSTOPERATIVE GASTRIC ILEUS IN ANESTHETIZED RATS

Objective The object of this study was to investigate the mechanisms o f postoperative gastric ileus in an experimental model of abdominal su rgery in anesthetized rats. Summary Background Data Sensory neurons pa rtly mediate postoperative gastric ileus. Among other neuropeptides, s ensory neurons contain calcitonin gene-related peptide (CGRP) and rele ase CGRP in response to noxious stimulation. Because CGRP inhibits gas tric motility, it was hypothesized that abdominal surgery stimulates s ensory neurons, which then releases CGRP, thereby inhibiting gastric m otility. Methods Postoperative ileus was induced by abdominal surgery. Gastric corpus motility was measured by an intragastric catheter. CGR P action was blocked by CGRP immunoneulralization or by a CGRP recepto r antagonist. Spinal sensory neurons were ablated by application of a sensory neurotoxin (capsaicin) to the celiac and superior mesenteric g anglia. Results Abdominal surgery decreased gastric corpus motility in the first 5 minutes after abdominal surgery by 59+/-5% and by 24+/-4% during the 1st postoperative hour. Capsaicin pretreatment of the celi ac and superior mesenteric ganglia, CGRP immunoneutralization, or CGRP receptor antagonism reversed the postoperative decrease in gastric co rpus motility during the Ist postoperative hour by 50%, 100%, and 59%, respectively. Conclusions These data indicate that spinal sensory neu rons and CGRP partly mediate postoperative gastric ileus. CGRP may be released from spinal sensory neuron terminals in the celiac and superi or mesenteric ganglia as part of an extraspinal intestinogastric inhib itory reflex activated by abdominal surgery.