title: Antinociceptive activity and pathway of the pallanalgesin isolated from venom of Agkistrodon halys (Pallas).
abstract: BACKGROUND
  Venom of Agkstrodon halys (Pallas) is a traditional Chinese medicine for the control of severe pain, but its analgesic mechanism is not clear.
  
  
  OBJECTIVE
  To isolate the analgesic fraction from the venom, evaluate the profile of its action on pain using preclinical nociceptive tests and determine the involvement of neurotransmitters in its action.
  
  
  METHODS
  Venom was separated with SPXL resin, and further purified by Superdex 75 and Superdex 30 resin. Its biochemical characteristics were analyzed including molecular weight (MW), isoelectric point (pI) and amino acid sequence. Animal pain models were applied including the hot plate test, acetic acid-induced writhing test, formalin test, Randall-Selitto pressure test, antagonistic test, spinalized rats test and intracerebral injection test. The endogenous neuropeptides leucine-enkephalin, β-endorphin and P substance were determined by HPLC in the tissues of brain and spinal cord.
  
  
  RESULTS
  An analgesic protein named pallanalgesin (MW 16.6 kDa, pI 8.8) was obtained from the venom of A. halys. It had significant antinociceptive activity in different animal pain models of thermal, chemical and mechanical stimulation. It effects both central and peripheral nerve systems, and it is related to opiate receptors and monoamines rather than acetylcholine receptors. Pallanalgesin could modulate the levels of neuropeptides in the brain and spinal cord, which contributes to the recovery of nerve injury and pain control.
  
  
  CONCLUSIONS
  As a novel analgesic, pallanalgesin has been found to explain the function of the venom of A. halys on severe pain control in traditional uses, and can be used as a new analgesic in the future.
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, PR China. yeyong@scut.edu.cn
authors.forename: Yong
authors.initials: Y
authors.lastname: Ye
authors.forename: Mingyang
authors.initials: M
authors.lastname: Li
authors.forename: Xuelan
authors.initials: X
authors.lastname: Chen
mesh_terms: D017836:Agkistrodon; D000700:Analgesics / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D008516:Medicine, Chinese Traditional; D051379:Mice; D009479:Neuropeptides / Q000378:metabolism; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D030162:Reptilian Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D012720:Severity of Illness Index; D013116:Spinal Cord / Q000378:metabolism
chemical_list: C031442:Agkistrodon venoms; D000700:Analgesics; D003435:Crotalid Venoms; D009479:Neuropeptides; D030162:Reptilian Proteins; C586323:pallanalgesin protein, Agkistrodon halys