Central Orexin-A stimulates pancreatic exocrine secretion via the vagus

Pancreas. 2002 Nov;25(4):400-4. doi: 10.1097/00006676-200211000-00013.


Introduction: Digestive organs are controlled from the central nervous system, and the vagus nerve plays an important role. Orexins are recently purified neuropeptides localized in neurons within the lateral hypothalamus.

Aim: To examine the effects of centrally injected Orexin-A and B on pancreatic exocrine secretion in conscious rats.

Methodology: Rats were prepared with cannulae draining bile and pancreatic juice separately. The experiments were conducted without anesthesia on day 4 or 5 after the operation.

Results: Intracerebroventricular administration of Orexin-A (0.25, 0.5, and 1.0 nmol) significantly increased pancreatic fluid and protein output in a dose-dependent manner. A significant stimulatory effect of Orexin-B was not observed. Pretreatment with the ganglion blocker hexamethonium and with atropine completely abolished the stimulatory effect of central Orexin-A. Central Orexin-A significantly increased pancreatic secretion after pretreatment with omeprazole. Intravenous injection of Orexin-A had no effect. Centrally administered Orexin-A stimulated the vagal efferent nerve in anesthetized rats.

Conclusions: Centrally administered Orexin-A stimulates pancreatic exocrine secretion through the vagal efferent nerve, and the stimulatory action is independent of gastric acid secretion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atropine / pharmacology
  • Carrier Proteins / administration & dosage
  • Carrier Proteins / antagonists & inhibitors
  • Carrier Proteins / pharmacology*
  • Ganglionic Blockers / pharmacology
  • Hexamethonium / pharmacology
  • Injections, Intravenous
  • Injections, Intraventricular
  • Intracellular Signaling Peptides and Proteins*
  • Kinetics
  • Male
  • Neuropeptides / administration & dosage
  • Neuropeptides / antagonists & inhibitors
  • Neuropeptides / pharmacology*
  • Omeprazole / pharmacology
  • Orexins
  • Pancreas / innervation*
  • Pancreas / metabolism*
  • Rats
  • Rats, Wistar
  • Vagus Nerve / drug effects
  • Vagus Nerve / physiology*


  • Carrier Proteins
  • Ganglionic Blockers
  • Intracellular Signaling Peptides and Proteins
  • Neuropeptides
  • Orexins
  • Hexamethonium
  • Atropine
  • Omeprazole