title: [Effect of transection or pretreatment of the infraorbital nerve with snake venom on the analgesia induced by electroacupuncture of "Sibai" (ST 2) acupoint in visceral pain rats].
abstract: OBJECTIVE
  To observe the role of large-diameter fibers of infraorbital nerve (ION) in "Sibai" (ST 2)-electroacupuncture (EA) induced analgesia in visceral pain (VP) rats.
  
  
  METHODS
  A total of 36 SD rats were randomized into control, VP, EA, ION transaction, snake venom (SV) and saline groups, with 6 rats in each group. EA(2 Hz/20 Hz) was applied to bilateral "Sibai" (ST 2) for 20 min. VP model was established by intraperitoneal injection of 0.6% acetic acid (10 mL/kg). Bilateral ION were transacted or pretreated by regional application of snake venom to selectively destroy A fibers,respectively. Behavior reactions were assessed by counting abdominal muscular contractions. Meanwhile, c-fos expression in the nucleus of the solitary tract (NTS) and paratrigeminal nucleus (PTN) was displayed by immunohistochemistry.
  
  
  RESULTS
  In comparison with control group, the numbers of abdominal muscular contraction,and c-fos immuno-reaction (IR) positive neurons in both NTS and PTN increased significantly in VP group (P < 0.001); while in comparison with VP group, the numbers of the abdominal contraction, and c-fos IR-positive neurons of both NTS and PTN in EA and SV and saline groups decreased considerably (P < 0.05, P < 0.01). No significant differences were found between ION transaction and VP groups in the abdominal contraction number, and c-fos IR-positive neurons in both NTS and PTN areas,and among EA and SV and saline groups in the numbers of abdominal contraction and c-fos IR-positive neurons of both NTS and PTN (P > 0.05).
  
  
  CONCLUSIONS
  The large-diameter (A) fibers of ION are not the major afferent fibers affecting EA-ST 2 induced analgesia in visceral pain rats; and somatic sensory afferents from orofacial areas and visceral pain input converge in the NTS and PTN, which may be the basis of the EA analgesia in the present study.
authors.affiliation: Key Laboratory for Studying Regularities and Mechanism of Acu-moxibustion, Department of Acu-moxibustion, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Fu
authors.forename: Zhen-Hua
authors.initials: ZH
authors.lastname: Xu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liao
authors.forename: Xin-Ran
authors.initials: XR
authors.lastname: Li
mesh_terms: D015667:Acupuncture Analgesia; D015669:Acupuncture Points; D000818:Animals; D003391:Cranial Nerves / Q000187:drug effects* / Q000378:metabolism; D004195:Disease Models, Animal; D015671:Electroacupuncture; D005260:Female; D006801:Humans; D008297:Male; D009437:Neuralgia / Q000209:etiology / Q000628:therapy*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012910:Snake Venoms / Q000633:toxicity*; D017552:Solitary Nucleus / Q000187:drug effects / Q000378:metabolism
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D012910:Snake Venoms