title: Down-regulation of GAP-43 by inhibition of caspases-3 in a rat model of neuropathic pain.
abstract: BACKGROUND
  Neuropathic pain remains a prevalent and persistent clinical problem due to incomplete understanding of its pathogenesis.
  
  
  OBJECTIVE
  The present study aimed to investigate the role of caspase-3 in the neuropathic pain in rats with chronic constriction injury (CCI).
  
  
  METHODS
  SD rats were randomly assigned four groups (n=18 per group): sham group, normal saline group (NS group), Z-DEVD-FMK group (DEVD group) and RNA interference group (siRNA group). Z-DEVD-FMK (1 U/30 μl), siRNA targeting caspase-3 (10 μg/30 μl) and NS of equal volume were intrathecally administered once daily for 5 days starting 1 day before surgery in the DEVD, siRNA and NS group, respectively. Thermal hyperalgesia was assessed at one day before and 1, 2, 4, 5, 6, 7 and 10 days after surgery. The mRNA and protein expressions of caspase-3 were measured by real time PCR and immunofluorescence assay. Apoptosis was detected by TUNEL staining. GAP-43 expression was measured by immunofluorescence and western blot assays.
  
  
  RESULTS
  The right paw withdrawal latency (PWL) was decreased after CCI (P<0.05). TUNEL-positive neurons and the mRNA and protein expressions of caspase-3 in the spinal cord were increased significantly. After Z-DEVD-FMK or siRNA treatment, TUNEL-positive neurons were decreased, PWLs increased (P<0.05) and the mRNA and protein expressions of caspase-3 decreased. The expression of GAP-43, a sprouting related protein, was decreased in the DEVD and siRNA group as compared to NS group (P<0.05). Up-regulation of GAP-43 following CCI was decreased following caspase-3 inhibition. Following sciatic nerve ligation, the gene expression, translation and transcription are significantly changed in the neurons which finally results in neuron apoptosis. The neuron apoptosis induce the up-regulation of GAP-43 expression leading to hyperalgesia.
  
  
  CONCLUSIONS
  Caspase-3 mediated neuron apoptosis is probably responsible for the neuropathic pain in CCI rats. Inhibition of caspase-3 may serve as a treatment of neuropathic pain.
authors.affiliation: Department of Anesthesiology, Eastern Hepatobiliary Hospital, the Second Military Medical University No. 225 Changhai Road, Shanghai 200433, China.
authors.forename: Feixiang
authors.initials: F
authors.lastname: Wu
authors.forename: Xuerong
authors.initials: X
authors.lastname: Miao
authors.forename: Jiaying
authors.initials: J
authors.lastname: Chen
authors.forename: Yuming
authors.initials: Y
authors.lastname: Sun
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Tao
authors.forename: Weifeng
authors.initials: W
authors.lastname: Yu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism*; D061945:Caspase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D015536:Down-Regulation; D005455:Fluorescent Antibody Technique; D019922:GAP-43 Protein / Q000378:metabolism*; D006930:Hyperalgesia / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology / Q000517:prevention & control; D020287:In Situ Nick-End Labeling; D007278:Injections, Spinal; D008297:Male; D009437:Neuralgia / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D013127:Spinal Nerves / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors
chemical_list: D061945:Caspase Inhibitors; D019922:GAP-43 Protein; D009842:Oligopeptides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: Apoptosis; GAP-43; RNA interference; caspase-3; neuropathic pain