Colonic elongation activates an intrinsic reflex that underlies slow transit and accommodation

It is generally believed that after-hyperpolarizing neurons are the only intrinsic sensory neurons in the gut wall. Recently, Smith and colleagues have demonstrated that some synaptic interneurons in the large bowel are activated by circumferential stretch and generate an ongoing motor activity even when AH neurons are silent. Further studies suggest that some descending interneurons are also mechanosensory since they are activated by longitudinal stretch rather than circumferential stretch. In particular, these mechanosensory neurons, which are NOS positive, respond to colonic elongation by releasing nitric oxide to reduce activity in intrinsic peristaltic circuits. This later reflex promotes storage by reducing the transit rate of fecal pellets down the
large bowel