Intraperitoneal capsaicin treatment reduces postoperative gastric ileus inawake rats

Introduction: Postoperative gastric ileus interferes with postoperative rec overy of the patients. Previous studies suggest that capsaicin-sensitive af ferent neurons are involved in the mediation of postoperative gastric ileus . Methods: A group of rats were equipped with a strain gauge transducer sut ured to the gastric wall. Gastric motility was recorded after intraperitone al injection of capsaicin (0.1 mu mol/kg and 1 mu mol/kg) or vehicle. The r ats were given 2 days of recovery before gastric motility was investigated in a postoperative ileus model. Results. Pretreatment with capsaicin 2 days prior to abdominal surgery significantly increased postoperative gastric m otility with complete recovery of gastric motility at 30 min postoperativel y (with the baseline motility index set at 100+/-4%, the gastric motility i ndex 30-45 min postoperatively was 64+/-4% for the vehicle, 138+/-20% for c apsaicin 0.1 mu mol/kg, and 110+/-12% for capsaicin 1 mu mol/kg: P=0.0008 v ehicle vs capsaicin). In contrast, capsaicin treatment 2 h prior to abdomin al surgery did not increase postoperative gastric motility (gastric motilit y index 30-45 min postoperatively was 64+/-4% for the vehicle and 51+/-8% f or capsaicin 0.1 mu mol/kg). The acute intraperitoneal injection of capsaic in decreased gastric motility by about 50-60%, the response lasting for 15- 30 min. Conclusions: Intraperitoneal capsaicin treatment 2 days prior to ab dominal surgery resulted in immediate recovery of postoperative gastric mot ility. indicating an important role for serosal visceral afferent nerve fib ers in the mediation of postoperative gastric ileus. Possibly, capsaicin or vanilloid (capsaicin) receptor agonists can be used to treat postoperative ileus in the future.