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

Critical Signaling Transduction Pathways and Intestinal Barrier: Implications for Pathophysiology and Therapeutics

The intestinal barrier is a sum of the functions and structures consisting of the intestinal mucosal epithelium, mucus, intestinal flora, secretory immunoglobulins, and digestive juices. It is the first-line defense mechanism that resists nonspecific infections with powerful functions that include physical, endocrine, and immune defenses. Health and physiological homeostasis are greatly dependent on the sturdiness of the intestinal barrier shield, whose dysfunction can contribute to the progression of numerous types of intestinal diseases. Disorders of internal homeostasis may also induce barrier impairment and form vicious cycles during the response to diseases. Therefore, the identification of the underlying mechanisms involved in intestinal barrier function and the development of effective drugs targeting its damage have become popular research topics. Evidence has shown that multiple signaling pathways and corresponding critical molecules are extensively involved in the regulation of the barrier pathophysiological state. Ectopic expression or activation of signaling pathways plays an essential role in the process of shield destruction. Although some drugs, such as molecular or signaling inhibitors, are currently used for the treatment of intestinal diseases, their efficacy cannot meet current medical requirements. In this review, we summarize the current achievements in research on the relationships between the intestinal barrier and signaling pathways. The limitations and future perspectives are also discussed to provide new horizons for targeted therapies for restoring intestinal barrier function that have translational potential.

Effects of denervation at ileocecal junction and ileocecal resection in dogs

BACKGROUND

To investigate neural regulation at the ileocecal junction (ICJ) and motility changes after ileocecal resection (ICR). Previous studies showed normal basal motility at the ICJ directly by force transducers in dogs, but these observations were limited to normal contractile activity.

METHODS

Continuous strain gauge recordings of stomach, terminal ileum, ileocecal sphincter (ICS), and colon were performed in dogs. The dogs were divided into four groups, namely control (CONT), extrinsic denervation at ICJ (ED), intrinsic denervation at ICJ (ID), and ICR groups. Colonic activity was recorded 2 h before a meal, in the early postprandial period (first 2 h), and in the late postprandial period (4-6 h after a meal). The meal lasted 5 min.

KEY RESULTS

Motility index was significantly increased at the ICS (P = 0.0056) and proximal colon (P = 0.0059) after feeding. However, such changes were not observed in the ED and ID groups. The amplitude of contractions at proximal colon in the interdigestive state was significantly decreased by ED. In the ID and ICR groups, the numbers of nonmigrating contractions were significantly decreased (P < 0.05), and colonic migrating motor complex (CMMC) ratio was significantly higher than that of the CONT group (P < 0.001). The dogs in these two groups had diarrhea.

CONCLUSIONS & INFERENCES

Gastrocolonic response at the ICJ may require both intrinsic and extrinsic innervation. When ID was performed, CMMC ratio increased. As a result, intraluminal water absorption may have decreased. ID may be one of the causes of diarrhea after ICR.