Propagation of giant migrating contractions between the small intestine, cecum and colon during radiation

Abstract

Background Radiation increases the frequency of small intestinal and colonic giant migrating contractions (GMCs). These contractions contribute to the diarrhea and cramping after radiation therapy and are coordinated with one another across the ileocolonic (IC) junction. Methods We investigated the coordination of contractile activity between the small intestine, cecum and colon in 5 canines following circumferential myotomy on the ileum at the IC junction and compared it to intact animals. Studies were performed before and during a radiation schedule. Key Results Myotomy increased the frequency of small intestinal GMCs prior to irradiation. In intact animals, the duration and amplitude of cecal GMCs decreased when multiple contractions occurred in rapid succession. This is in contrast to small intestinal and colonic GMCs and suggests a different mechanism of propagation for GMCs within the cecum. Ileal myotomy dramatically decreased the frequency of propagating radiation induced colonic GMCs. The total number of colonic GMCs was not altered. Colonic contractile activity was disrupted in intact animals during irradiation. However, after ileal myotomy, irradiation did not affect the pattern of colonic contractile states. Diarrhea in irradiated animals with myotomy started earlier than intact animals. This may be related to the frequency of small intestinal GMCs. Conclusions & Inferences Our findings suggest importance of the enteric neural connections at the IC region to contractile disorders of both the small and large intestine. The anatomic relationship between the canine IC junction is similar to the human ileo-appendiceal-colonic region and surgical manipulations of this area may likewise affect human contractile activity.

Effects of denervation at ileocecal junction and ileocecal resection in dogs

“…We observed a giant migrating contraction at the ICS (distal to the denervation point). Our results were similar to those of Otterson et al 25 Sarna et al 13 reported that GCR comprises three phases such as immediate (0-5 min after ingestion of a meal), early (0-2 h after ingestion), and late phase (2-8 h after ingestion). In our study, GCR both in early and late states at the proximal colon was significantly inhibited not only in ED group but also in ID group.…”

“…Possibly, this trigger may propagate via intrinsic nerves. Otterson et al 25 showed that intrinsic denervation at the terminal In the control group, there were no effects of meal ingestion. In the ID group, the mean duration of contractile activity significantly decreased at various sites.…”

“…Otterson et al. 25 showed that intrinsic denervation at the terminal ileum caused an increase in the ileal giant migrating contraction proximal to the denervation point. However, the giant migrating contraction that propagated across the ICJ decreased.…”

Toxoplasma gondii infection impairs the colonic motility of rats due to loss of myenteric neurons

“…However, ours is a mild model of infection, and in a clinical setting it may be expected that more severe changes would occur. Thus, slower, longer contraction complexes would be more efficient in forcing content aborally, predisposing to episodic diarrhea 49 . The more this pattern of motility predominates, the more likely content will be shifted aborally 50 .…”

The impact of dietary fibres on the physiological processes governing small intestinal digestive processes

“…This action also heralds the commencement of the intestinal phase of digestion. The motility pattern within the intestinal phase of digestion consists of migrating, clustered contractions that tend to move contents along the small intestine up to 30 centimetres at a time at varying frequencies (Otterson, Leming, Fox, & Moulder, 2010;Otterson & Sarr, 1993). Segmentation along the small intestine ensures adequate mixing of luminal contents with digestive juices and improves the chances of contact with the villi (Gwynne, Thomas, Goh, Sjövall, & Bornstein, 2004;Huizinga & Lammers, 2009).…”