Bladder, Bowel, and Sexual Dysfunction in Parkinson's Disease
Figure 4
Enteric neural circuitry relevant to peristaltic reflex. Following mucosal stimulation, 5-HT is released from enterochromaffin cells to intrinsic primary sensory neurons (with 5-HT3 and 5-HT4 receptors) and extrinsic vagal and spinal sensory neurons (with 5-HT3 receptors). Sensory neurons release calcitonin gene-regulated peptide (CGRP), substance (SP), and acetylcholine (ACh) to interneurons. Interneurons release ACh and SP orally to excitatory motorneurons while ACh is released aborally to inhibitory motorneurons. Excitatory motorneurons release ACh and SP to smooth muscle cells while inhibitory motorneurons release nitric oxide (NO), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP), and adenosine triphosphate (ATP) to smooth muscle cells. 5-HT also acts as an excitatory modulator on motor neurons (with 5-HT3 and 5-HT4 receptors) whereas dopamine seems to be an inhibitory modulator on motor neurons (with receptor). Interstitial cells of Cajal (ICC) interact with smooth muscle cells for generating rhythmicity (with Ach, VIP, and NO receptors).
