title: Cancer-induced bone pain sequentially activates the ERK/MAPK pathway in different cell types in the rat spinal cord.
abstract: BACKGROUND
  Previous studies have demonstrates that, after nerve injury, extracellular signal-regulated protein kinase (ERK) activation in the spinal cord-initially in neurons, then microglia, and finally astrocytes. In addition, phosphorylation of ERK (p-ERK) contributes to nociceptive responses following inflammation and/or nerve injury. However, the role of spinal cells and the ERK/MAPK pathway in cancer-induced bone pain (CIBP) remains poorly understood. The present study analyzed activation of spinal cells and the ERK/MAPK pathway in a rat model of bone cancer pain.
  
  
  RESULTS
  A Sprague Dawley rat model of bone cancer pain was established and the model was evaluated by a series of tests. Moreover, fluorocitrate (reversible glial metabolic inhibitor) and U0126 (a MEK inhibitor) was administered intrathecally. Western blots and double immunofluorescence were used to detect the expression and location of phosphorylation of ERK (p-ERK). Our studies on pain behavior show that the time between day 6 and day 18 is a reasonable period ("time window" as the remaining stages) to investigate bone cancer pain mechanisms and to research analgesic drugs. Double-labeling immunofluorescence revealed that p-ERK was sequentially expressed in neurons, microglia, and astrocytes in the L4-5 superficial spinal cord following inoculation of Walker 256 cells. Phosphorylation of ERK (p-ERK) and the transcription factor cAMP response element-binding protein (p-CREB) increased in the spinal cord of CIBP rats, which was attenuated by intrathecal injection of fluorocitrate or U0126.
  
  
  CONCLUSIONS
  The ERK inhibitors could have a useful role in CIBP management, because the same target is expressed in various cells at different times.
authors: Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
authors: Li-na
authors: LN
authors: Wang
authors: Ming
authors: M
authors: Yao
authors: Jian-ping
authors: JP
authors: Yang
authors: Jun
authors: J
authors: Peng
authors: Yan
authors: Y
authors: Peng
authors: Cai-fang
authors: CF
authors: Li
authors: Yan-bing
authors: YB
authors: Zhang
authors: Fu-hai
authors: FH
authors: Ji
authors: Hao
authors: H
authors: Cheng
authors: Qi-nian
authors: QN
authors: Xu
authors: Xiu-yun
authors: XY
authors: Wang
authors: Jian-ling
authors: JL
authors: Zuo
mesh_terms: D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001859:Bone Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D002070:Butadienes / Q000008:administration & dosage / Q000494:pharmacology; D002951:Citrates / Q000008:administration & dosage / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006930:Hyperalgesia / Q000150:complications / Q000473:pathology; D007278:Injections, Spinal; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009570:Nitriles / Q000008:administration & dosage / Q000494:pharmacology; D009928:Organ Specificity / Q000187:drug effects; D010146:Pain / Q000201:enzymology* / Q000209:etiology* / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D013977:Tibia / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology
chemical_list: D000700:Analgesics; D002070:Butadienes; C508137:Creb1 protein, rat; D002951:Citrates; D017362:Cyclic AMP Response Element-Binding Protein; D009570:Nitriles; C113580:U 0126; C007744:fluorocitrate; D048049:Extracellular Signal-Regulated MAP Kinases