The importance of interstitial cells of cajal in the gastrointestinal tract

Abstract

Gastrointestinal (GI) motility function and its regulation is a complex process involving collaboration and communication of multiple cell types such as enteric neurons, interstitial cells of Cajal (ICC), and smooth muscle cells. Recent advances in GI research made a better understanding of ICC function and their role in the GI tract, and studies based on different types of techniques have shown that ICC, as an integral part of the GI neuromuscular apparatus, transduce inputs from enteric motor neurons, generate intrinsic electrical rhythmicity in phasic smooth muscles, and have a mechanical sensation ability. Absence or improper function of these cells has been linked to some GI tract disorders. This paper provides a general overview of ICC; their discovery, subtypes, function, locations in the GI tract, and some disorders associated with their loss or disease, and highlights some controversial issues with regard to the importance of ICC in the GI tract.

Figure 1

Overview of the types of interstitial cells of cajal in the gastrointestinal tract. (a-c): Schematic representations of ICC in the stomach (a), small intestine (b), and colon (c). ICC-MY (blue) are located between circular (CM) and longitudinal (LM) muscle layers. ICC-IM (red) and ICC-DMP (red) are located within circular and longitudinal muscles. ICC-SM (green) are located at the submucosal surface of the circular muscle layer in the colon. Redrawn from Satoshi Iino and Kazuhide Horiguchi, Acta Histochem Cytochem. 2006 December 28; 39(6): 145-153

Figure 2

Absence of slow waves in W/W^v mice. Normal slow waves recorded in wild-type control mice small intestine smooth muscles (a) are lost in W/W^V mutant mice; (b) Ward et al., 1994. J. Physiol. London 480:91-97

Figure 3

Innervation of smooth muscle cells. Two mechanisms for neuronal innervation of gastrointestinal smooth muscle exist. Most innervation occurs through interstitial cells of Cajal. Neurons can also directly innervate intestinal smooth muscle cells. Redrawn from Mazzone A, Farrugia G. Evolving concepts in the cellular control of gastrointestinal motility: Neurogastroenterology and enteric sciences. Gastroenterol Clin North Am 36: 499-513, 2007