title: Effect of orexin-A (hypocretin-1) on hyperalgesic and cachectic manifestations of experimentally induced rheumatoid arthritis in rats.
abstract: Orexin-A has been shown to modulate pain sensation and increase appetite. Rheumatoid arthritis (RA) is characterized by joint destruction, deformity, hyperalgesia, and weight reduction.
  
  
  OBJECTIVE
  Evaluate the possible effect of orexin-A on hyperalgesic and cachectic manifestations in an adjuvant-induced arthritis (AIA) rat model.
  
  
  METHODS
  Forty adult male Wistar rats were distributed among 4 groups; I, normal controls; II, rats with AIA induced by intradermal injection of Mycobacterium butyricum, but with no other treatment; III, AIA rats treated daily with an intravenous injection of orexin-A for 8 days; and IV, AIA rats treated orally with dexamethasone for 8 days. The parameters we assessed were pain-associated behavior, body mass, hind paw volume, serum levels of nerve growth factor (NGF) and neuropeptide Y (NPY).
  
  
  RESULTS
  Orexin-A caused a significant reduction in pain sensation and NGF levels, and increased body mass and the levels of NPY, whereas treatment with dexamethasone led to significant reductions in paw swelling and pain sensation.
  
  
  CONCLUSIONS
  Orexin-A has hypoalgesic properties and increases body mass, whereas dexamethasone has a potent anti-inflammatory effect. Therefore, the combination of orexin-A and dexamethasone should have a greater effect with respect to attenuating the manifestations and complications associated with RA.
authors.affiliation: a Physiology Department, Faculty of Medicine, Alexandria University, Egypt.
authors.forename: Adham R
authors.initials: AR
authors.lastname: Mohamed
authors.forename: Wessam F
authors.initials: WF
authors.lastname: El-Hadidy
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000503:physiopathology; D003907:Dexamethasone / Q000494:pharmacology / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D006930:Hyperalgesia / Q000188:drug therapy* / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology / Q000627:therapeutic use*; D000068797:Orexins; D010147:Pain Measurement; D017208:Rats, Wistar; D015431:Weight Loss / Q000187:drug effects*
chemical_list: D000893:Anti-Inflammatory Agents; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D003907:Dexamethasone
keywords: adjuvant-induced arthritis; arthrite induite par adjuvant; cachexia; cachexie; dexamethasone; dexaméthasone; enflure de la patte arrière; facteur de croissance neural; hind paw swelling; nerve growth factor; neuropeptide Y