SB-334867, a selective orexin-1 receptor antagonist, enhances behavioural satiety and blocks the hyperphagic effect of orexin-A in rats

Eur J Neurosci. 2001 Apr;13(7):1444-52. doi: 10.1046/j.0953-816x.2001.01518.x.


Intracerebroventricular (i.c.v.) administration of the novel hypothalamic neuropeptide orexin-A stimulates food intake in rats, and delays the onset of behavioural satiety (i.e. the natural transition from feeding to resting). Furthermore, preliminary findings with the selective orexin-1 receptor antagonist, SB-334867, suggest that orexin-A regulation of food intake is mediated via the orexin-1 receptor. At present, however, little is known about either the intrinsic effects of SB-334867 on the normal structure of feeding behaviour, or its effects upon orexin-A-induced behavioural change. In the present study, we have employed a continuous monitoring technique to characterize the effects of SB-334867 (3-30 mg/kg, i.p.) on the microstructure of rat behaviour during a 1-h test with palatable wet mash. Administered alone, SB-334867 (30 mg/kg, but not lower doses) significantly reduced food intake and most active behaviours (eating, grooming, sniffing, locomotion and rearing), while increasing resting. Although suggestive of a behaviourally nonselective (i.e. sedative) action, the structure of feeding behaviour was well-preserved at this dose level, with the reduction in behavioural output clearly attributable to an earlier onset of behavioural satiety. As previously reported, orexin-A (10 microg per rat i.c.v.) stimulated food intake, increased grooming and delayed the onset of behavioural satiety. Pretreatment with SB-334867 dose-dependently blocked these effects of orexin-A, with significant antagonism evident at dose levels (3-10 mg/kg) below those required to produce intrinsic behavioural effects under present test conditions. Together, these findings strongly support the view that orexin-A is involved in the regulation of feeding patterns and that this influence is mediated through the orexin-1 receptor.

MeSH terms

  • Animals
  • Appetitive Behavior / drug effects
  • Benzoxazoles / pharmacology*
  • Body Weight
  • Carrier Proteins / pharmacology*
  • Eating / drug effects
  • Hyperphagia / chemically induced
  • Hyperphagia / metabolism*
  • Injections, Intraventricular
  • Intracellular Signaling Peptides and Proteins*
  • Male
  • Naphthyridines
  • Neuropeptides / pharmacology*
  • Orexin Receptors
  • Orexins
  • Rats
  • Rats, Inbred Strains
  • Receptors, G-Protein-Coupled
  • Receptors, Neuropeptide / antagonists & inhibitors*
  • Receptors, Neuropeptide / metabolism
  • Satiety Response / drug effects*
  • Urea / analogs & derivatives
  • Urea / pharmacology*


  • 1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea
  • Benzoxazoles
  • Carrier Proteins
  • Intracellular Signaling Peptides and Proteins
  • Naphthyridines
  • Neuropeptides
  • Orexin Receptors
  • Orexins
  • Receptors, G-Protein-Coupled
  • Receptors, Neuropeptide
  • Urea