Multifunctional mechanosensitive neurons in the enteric nervous system

One of the most intriguing abilities of the gut is to function in isolation. This is possible because the gut's own nervous system, the enteric nervous system, contains the necessary elements to control reflex behaviors. Much progress has been made in identifying those neurons that encode mechanical or chemical stimuli. Thus, muscle behaviors in the small and large intestines depend on mechanosensitive neurons which encode a variety of mechanical stimuli, ranging from brief deformation of the neurons soma or processes to sustained tissue stretch. Mechanosensitivity has been recorded in a wide variety of neurons which behave like rapid or slowly adapting mechanosensors. Strikingly, mechanosensitive neurons do not appear to belong to a distinct class of highly specialised neurons but rather differ in their electrophysiology, neurochemistry and morphology. While some mechanosensitive neurons may respond to one stimulus type others appear to be polymodal. Available data would suggest that mechanosensitive enteric neurons are multitasking and hence belong to multifunctional circuits. This review summarises the main arguments in favour of this concept, discusses the stimulus modalities, the response patterns and the functional role of mechanosensitive enteric neurons and concludes with identifying future challenges.