Differential 5-HT₃ mediation of human gastrocolonic response and colonic peristaltic reflex

Abstract

Colonic motor function is modulated by extended and local neural reflexes involving unknown mediators. To test the role of serotonin (5-HT3) pathways, increases in colonic tone during antral distension and duodenal lipid perfusion (gastrocolonic responses) and changes in orad and caudad colonic tone in response to local colonic distension (peristaltic reflex) were measured after double-blind granisetron (10 μg/kg) or placebo infusion in healthy human volunteers. Antral distension evoked increases in colonic tone, which were blunted by granisetron ( P < 0.05) without effects on antral compliance. Intraduodenal lipid perfusion also evoked increased colonic tone, which was reduced by granisetron ( P < 0.05). In contrast, orad colonic contractions and caudad relaxations and contractions during colonic distension were unaffected by granisetron. In conclusion, 5-HT3 receptor antagonism blunts both the mechano- and chemoreceptor components of the human gastrocolonic response without altering antral compliance. In contrast, 5-HT3 pathways play no role in the ascending or descending components of the colonic peristaltic reflex. These findings demonstrate different roles for 5-HT3 receptors in the control of colonic motor function by the proximal gastrointestinal tract and by local neural reflexes.

Modulatory influences on antegrade and retrograde tonic reflexes in the colon and rectum

“…Descending inhibitory inputs may modulate this reflex. The neural pathways involved in the colorectal reflex are less apparent but are likely to have some similarities to other "long" reflexes, including the descending gastrocolic reflex, where a variety of neuropeptide mediators, receptors, and pathways have been implicated (2,11,16). The exact neural pathways for both reflexes are, however, yet to be precisely defined and require further studies.…”

Gastrointestinal influence on the electrophysiology of the heart: induction of cardiac arrhythmic episodes by myoelectrical uncoupling within the gut

“…The peristaltic process continues into the colon where intestinal motility is dependent on the colonic reflex, which is comprised of distention-sensitive mechanoreceptors of the antrum and nutrient-sensitive chemoreceptors located in the mucosa of the small intestines (Björnsson et al, 1998). The function of the colonic reflex involves gastrocolonic responses from antral distention and duodenal lipid perfusion.…”

<i>H. pylori</i> Infection and Visceral Hypersensitivity in Patients with Irritable Bowel Syndrome

“…To understand the pathophysiologic pathway, several aspects have to be taken into consideration: A reflex between stomach and colon first has been described in 1912 and further evaluated in the last 30 years. The 'gastrocolonic response' is a well-characterized colonic reflex which consists of two components: a mechanoreceptor-mediated early component activated by antral distension and a chemoreceptor-mediated later component initiated by nutrient contact with the small intestinal mucosa [13].…”

“…Little is known about H. pylori effects on the lower intestinal tract, although gastric factors are known to induce reflex activities in the colon, known as the gastrocolonic reflex [13]. The aim of this study is to determine whether the barostat distension is able to induce abdominal symptoms in patients with the clinical presentation of IBS and whether H. pylori infection may have a modulating influence on colonic reflexes.…”