title: Involvement of spinal orexin A in the electroacupuncture analgesia in a rat model of post-laparotomy pain.
abstract: BACKGROUND
  Orexin A (OXA, hypocretin/hcrt 1) is a newly discovered potential analgesic substance. However, whether OXA is involved in acupuncture analgesia remains unknown. The present study was designed to investigate the involvement of spinal OXA in electroacupuncture (EA) analgesia.
  
  
  METHODS
  A modified rat model of post-laparotomy pain was adopted and evaluated. Von Frey filaments were used to measure mechanical allodynia of the hind paw and abdomen. EA at 2/15 Hz or 2/100 Hz was performed once on the bilateral ST36 and SP6 for 30 min perioperatively. SB-334867, a selective orexin 1 receptor (OX1R) antagonist with a higher affinity for OXA than OXB, was intrathecally injected to observe its effect on EA analgesia.
  
  
  RESULTS
  OXA at 0.3 nmol and EA at 2/15 Hz produced respective analgesic effects on the model (P<0.05). Pre-surgical intrathecal administered of SB-334867 30 nmol antagonized OXA analgesia and attenuated the analgesic effect of EA (P<0.05). However, SB-334867 did not block fentanyl-induced analgesia (P>0.05). In addition, naloxone, a selective opioid receptor antagonist, failed to antagonize OXA-induced analgesia (P>0.05).
  
  
  CONCLUSIONS
  The results of the present study indicate the involvement of OXA in EA analgesia via OX1R in an opioid-independent way.
authors.affiliation: Department of Integrative Medicine and Neurobiology, Institute of Acupuncture Research, WHO Collaborating Center for Traditional Medicine, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 20032, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Feng
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Mi
authors.forename: Fang
authors.initials: F
authors.lastname: Xia
authors.forename: Qi-Liang
authors.initials: QL
authors.lastname: Mao-Ying
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Jiang
authors.forename: Sheng
authors.initials: S
authors.lastname: Xiao
authors.forename: Zhi-Fu
authors.initials: ZF
authors.lastname: Wang
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Wang
authors.forename: Gen-Cheng
authors.initials: GC
authors.lastname: Wu
mesh_terms: D000005:Abdomen; D015669:Acupuncture Points; D000698:Analgesia / Q000379:methods*; D000818:Animals; D015671:Electroacupuncture / Q000379:methods*; D005283:Fentanyl / Q000494:pharmacology; D006614:Hindlimb; D006930:Hyperalgesia / Q000378:metabolism / Q000628:therapy; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D007813:Laparotomy; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009479:Neuropeptides / Q000378:metabolism*; D064446:Orexin Receptors; D000068797:Orexins; D010146:Pain / Q000378:metabolism*; D059408:Pain Management / Q000379:methods; D011183:Postoperative Complications / Q000378:metabolism / Q000628:therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000378:metabolism*; D013131:Spine / Q000378:metabolism*
chemical_list: C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009292:Narcotic Antagonists; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D009270:Naloxone; D005283:Fentanyl