Preoperative intraluminal application of capsaicin increases postoperativegastric and colonic motility in rats

In a model to investigate postoperative gastrointestinal motility with stra in gauge transducers in awake rats, we tested the effects of intraluminal c apsaicin infusion into the cecum 2 days or 14 days prior to abdominal surge ry Acute infusion of capsaicin into the cecum for 30 minutes increased the gastric, small intestinal, and colonic motility index by up to 115%, 34%, a nd 59%, respectively, compared to vehicle infusion. Intraluminal capsaicin infusion 2 days prior to abdominal surgery significantly increased the intr aoperative gastric and colonic motility index by 166% and 100%, respectivel y, compared to vehicle, but had no effect on small intestinal motility The postoperative decrease in gastric or colonic motility was completely preven ted by capsaicin pretreatment, representing a 73% and a 72% increase in the motility index during the first postoperative hour and a 40% and a 29% inc rease in the motility index during the second postoperative hour compared t o vehicle, whereas the postoperative decrease in small intestinal motility was not altered by capsaicin pretreatment. In contrast, intraluminal capsai cin infusion 14 days prior to abdominal surgery had no effect on postoperat ive inhibition of gastrointestinal motility. Our results suggest that capsa icin-sensitive visceral afferent C-fibers, presumably of the submucosa, pia v an important role in mediating postoperative ileus. Intraluminal capsaici n does probably ablate these nerve fibers temporarily, with no systemic sid e effects observed with the use of the tail flick test as a measure of skin nociception.