Actions of orexin-A in the myenteric plexus of the guinea-pig small intestine.
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.
Katayama
Yoshifumi
Y
Department of Autonomic Physiology, Medical Research Institute, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan. kataauto@tmd.ac.jp
Homma
Tomoo
T
Honda
Kazuki
K
Hirai
Keiji
K
D000818:Animals; D002352:Carrier Proteins / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects* / Q000294:innervation; D047908:Intracellular Signaling Peptides and Proteins; D008839:Microelectrodes; D009197:Myenteric Plexus / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects; D009479:Neuropeptides / Q000494:pharmacology*; D000068797:Orexins
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins