Neuronal control in gastrointestinal disease.

This short review is based on only a small selected sample of research to illustrate the wide variety of cellular mechanisms that underlie the neural basis of digestive diseases. The enteric nervous system and its effector cells are involved in the control of most gastrointestinal activities. The review summarises the neural mechanisms involved in normal and abnormal gastrointestinal functions. The gastrointestinal tract is exposed to a tremendous variety of foreign substances including those ingested with food and those produced by the extensive commensal and pathological bacterial flora. Normal functions controlled by the enteric neural circuits are well adapted to distinguish nutrients from harmful stimuli. The main enteric neural circuits have been identified in experimental animals and are being investigated in humans. The enormous variety of motor patterns observed in normal gastrointestinal tract is the result of interplay of a few fundamental mechanisms, including myogenic mechanisms; neurogenic accommodation, neurogenic propulsive mechanisms and migrating neurogenic motor activity. Motor dysfunctions of the gut are likely to be caused by abnormalities of one or more of these mechanisms. Disturbances of enteric neural functions can arise from physiological defence reactions to harmful insults, from abnormal activation of physiological circuits, or from pathological alterations of the enteric circuits. Vomit and expulsive propulsion and inflammation or bacteria neurally induced changes in motility are physiological defence mechanisms. Pathological alterations include toxic, autoimmune, genetic lesions also secondary to systemic diseases and can be partial and graded.