Table 1.

EP receptor signaling pathways and cellular localization in the normal large intestine

ReceptorSecond Messenger SignalTissue LocalizationPhysiologic Role in the GI Tract
EP1*Phospholipase C/inositol trisphosphateEpithelium (H), epithelium, glial cells, and longitudinal muscle (R)GI tract motility (R)
EP2Increased cAMPEpithelium (R)Chloride secretion (H)
EP3Decreased cAMPEpithelium (H), epithelium, glial cells, and longitudinal muscle (R)Duodenal bicarbonate secretion (M) and GI tract motility (R)
EP4Increased cAMPEpithelium and lamina propria cells (H), and epithelium (M and R)Gastric mucus production (R) and chloride secretion (H)
  • NOTE: H, human (25–27); M, mouse (28); and R, rat (29, 30).

  • * There are two human EP1 splice variants.

  • mRNAs for all four EP receptors are strongly expressed by goblet cells in rat colonic epithelium (29).

  • There are eight human EP3 splice variants; at least one of which mediates an increase in intracellular cAMP levels via Gs. Activation of at least two EP3 isoforms also leads to increased inositol trisphosphate levels via Gq.