The effect of orexin-A and -B on the histamine release in the anterior hypothalamus in rats

Neurosci Lett. 2002 Apr 26;323(2):93-6. doi: 10.1016/s0304-3940(01)02552-6.


The neuropeptides orexin-A and -B have been reported to be appetite-stimulating peptides, but they are also known as important factors that control arousal state. We studied the effects of orexin-A and -B on the hypothalamic histamine release using in vivo microdialysis. A significant and sustained increase in histamine release was observed by intracerebroventricular injection of 1 nmol of orexin-A, but not by the same dose of orexin-B. An increased dose of orexin-B to 5 nmol facilitated histamine release, although this effect was much less potent than orexin-A. These findings suggest that both of the orexins play important roles in the regulation of waking through the activation of histaminergic system.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Carrier Proteins / pharmacology*
  • Carrier Proteins / physiology
  • Histamine Release / drug effects*
  • Histamine Release / physiology
  • Hypothalamus, Anterior / drug effects*
  • Hypothalamus, Anterior / metabolism
  • Intracellular Signaling Peptides and Proteins*
  • Male
  • Neuropeptides / pharmacology*
  • Neuropeptides / physiology
  • Orexins
  • Rats
  • Rats, Wistar
  • Up-Regulation / drug effects


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