Abstract 1884 The Molecular Mechanism for Reversed Dopamine D2 Receptor Cellular Output and Defecation Control, Enabled by Constitutive Ghrelin Receptor Activity

Dopamine is likely to be the relevant neurotransmitter responsible for coordinating voluntary defecation in the lumbro-sacral defecation center. In these neurons dopamine acts via the dopamine D2 receptor (DRD2) and atypically elicits excitatory responses, leading to increased colonic motility. These neurons also express the ghrelin receptor (GHSR), whose agonist, ghrelin, appears to be absent from the central nervous system, yet stimulating this receptor also increases colonic motility. In intact animals, we have shown a functional interaction between DRD2 and GHSR in controlling colonic motility.