Actions of orexin-A in the myenteric plexus of the guinea-pig small intestine

Neuroreport. 2003 Aug 6;14(11):1515-8. doi: 10.1097/00001756-200308060-00023.


Orexins and orexin-receptors are localized by displaying their immunoreactivity in the enteric nervous system. Intracellular recordings were made from isolated myenteric neurons to investigate actions of orexin-A in the myenteric plexus of the guinea-pig ileum. Superfusion of orexin-A caused membrane depolarizations in a subset of S and AH neurons. Orexin-A responses were preserved in Ca2+ free/high Mg2+ solution and associated with an increase in input membrane resistance; their reversal potential was about -90 mV. Orexin-A augmented nicotinic fast EPSPs, whereas it did not affect the postsynaptic sensitivity to acetylcholine; this indicates that orexin-A increased the presynaptic release of acetylcholine. In conclusion, orexin-A contributes in the regulation of gut motility via its pre- and postsynaptic actions in the myenteric plexus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carrier Proteins / pharmacology*
  • Excitatory Postsynaptic Potentials / drug effects
  • Guinea Pigs
  • Ileum / drug effects
  • In Vitro Techniques
  • Intestine, Small / drug effects*
  • Intestine, Small / innervation
  • Intracellular Signaling Peptides and Proteins*
  • Microelectrodes
  • Myenteric Plexus / drug effects*
  • Neurons / drug effects
  • Neuropeptides / pharmacology*
  • Orexins


  • Carrier Proteins
  • Intracellular Signaling Peptides and Proteins
  • Neuropeptides
  • Orexins