title: Effects of orexin and glucose microinjected into the hypothalamic paraventricular nucleus on gastric acid secretion in conscious rats.
abstract: BACKGROUND
  Orexin-A is a novel peptide that appears to play a role in regulation of gastric acid secretion. However, little is known about sites of its action. In addition, evidences suggest that some of orexin-A neurons respond to glucose. In this study, we address the hypothesis which demonstrates that orexin-A and glucose act in the hypothalamic paraventricular nucleus (PVN) to increase gastric acid secretion and juice volume in pyloric-ligated conscious rats.
  
  
  METHODS
  Male Wistar rats were implanted with guide canula directed to the PVN. Orexin-A (3-10 μg), glucose (350-750 ng) SB334867 (6-20 μg) were microinjected. The effect of pretreatment with an orexin-1 receptor antagonist, SB334867, on orexin-A and D-glucose induced acid secretion was assessed. Gastric acid secretion was measured using the pylorus-ligation method, and the amount of gastric acid was determined by titration with 0.01 N NaOH to a pH of 7.0.
  
  
  RESULTS
  Intraparaventricular injection of orexin-A or D-glucose stimulated gastric acid secretion in a dose-dependent manner. The PVN injections of orexin-A receptor antagonist, SB334867, were associated with gastric acid secretion decrease and inhibited effects of PVN-injected orexin-A. Orexin-stimulated gastric acid secretion was decreased (~40%) after PVN lesions. Glucose-stimulated gastric acid secretion was also suppressed by intraperitoneal (IP) injection of SB334867. In addition, it was observed that co-injection of orexin-A and glucose at ineffective doses increased gastric secretion significantly.
  
  
  CONCLUSIONS
  We suggest that orexin-A and glucose effects on the PVN stimulate gastric acid secretion. This stimulatory effect is probably mediated by orexin-1 receptors.
authors: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors: N
authors: N
authors: Chaleek
authors: M
authors: M
authors: Kermani
authors: A
authors: A
authors: Eliassi
authors: A
authors: A
authors: Haghparast
mesh_terms: D000818:Animals; D001583:Benzoxazoles / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D009287:Naphthyridines; D009479:Neuropeptides / Q000494:pharmacology*; D000068797:Orexins; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; D047908:Intracellular Signaling Peptides and Proteins; D009287:Naphthyridines; D009479:Neuropeptides; D000068797:Orexins; D014508:Urea; D005947:Glucose