Changes in interstitial cells of Cajal at the deep muscular plexus are associated with loss of distention-induced burst-type muscle activity in mice infected by Trichinella spiralis.

The physiology and pathophysiology of the network of interstitial cells of Cajal associated with the deep muscular plexus (ICC-DMP) of the small intestine are still poorly understood. The objectives of the present study were to evaluate the effects of inflammation associated with Trichinella spiralis infection on the ICC-DMP and to correlate loss of function with structural changes in these cells and associated structures. We used immunohistochemistry, electron microscopy, and assessment of distention-inducing electrophysiological parameters in vitro. Damage to ICC-DMP was associated with a loss of distention-induced patterns of electrical activity normally associated with distention-induced peristalsis. Consistently, the timing of recovery of ICC-DMP paralleled the timing of recovery of the distention-induced activity. Nerve varicosities associated with ICC-DMP including cholinergic nerves, assessed by immunoelectron microscopy and whole mount double labeling, paralleled injury to ICC-DMP thus contributing to impaired excitatory innervation of smooth muscle cells. Major additional changes included a remodeling of the inner circular muscle layer, which may affect long-term sensitivity to distention after infection. In conclusion, transient injury to ICC-DMP in response to T. spiralis infection is severe and associated with a complete lack of distention-induced burst-type muscle activity.