Mechanism of abnormal intestinal motility in inflammatory bowel disease: how smooth muscle contraction is reduced?

Intestinal inflammation alters the contractile activity of intestinal smooth muscle. Motility disorders of the gastrointestinal tract are clinically important symptoms, because they are often associated with severe interstitial inflammation. In addition, the motility disorders secondarily induce abnormal growth of the intestinal flora, and the resulting disturbance of this flora aggravates the pathogenesis of mucosal inflammation. This in turn aggravates the intestinal dysmotility; i.e., it is an inflammatory spiral. Therefore, it is important to elucidate the mechanisms involved in the changes in motor function which occur in intestinal inflammation. Recent studies have revealed several molecular mechanisms responsible for the decreased motility which occurs in an inflamed gastrointestinal tract. In the present review, we discuss the functional failure of smooth muscle cells, including changes in the activity of muscarinic receptors, ion channels and the endogenous myosin phosphatase inhibitor CPI-17.