title: Chronic intrathecal infusion of T-type calcium channel blockers attenuates CaV3.2 upregulation in nerve-ligated rats.
abstract: OBJECTIVE
  T-type channel (TCC) CaV3.2 plays a pivotal role in pain transmission. In this study, we examined the effects of intrathecal TCC blockers on CaV3.2 expression in a L5/6 spinal nerve ligation (SNL) pain model. The neurotoxicity of TCC blockers were also evaluated.
  
  
  METHODS
  Male Sprague-Dawley rats (200-250 g) were used for right L5/6 SNL to induce neuropathic pain. Intrathecal infusion of saline or TCC blockers [mibefradil (0.7 μg/h) or ethosuximide (60 μg/h)] was started after surgery for 7 days. Fluorescent immunohistochemistry and Western blotting were used to determine the expression pattern and protein level of CaV3.2. Hematoxylin-eosin and toluidine blue staining were used to evaluate the neurotoxicity of tested agents.
  
  
  RESULTS
  Seven days after SNL, CaV3.2 protein levels were upregulated in ipsi-lateral L5/6 spinal cord and dorsal root ganglia (DRG) in immunofluorescence and Western blotting studies. Compared with the saline-treated group, rats receiving mibefradil or ethosuximide showed significant lower CaV3.2 expression in the spinal cord and DRG. No obvious histopathologic change in hematoxylin-eosin and toluidine blue staining were observed in all tested groups.
  
  
  CONCLUSIONS
  In this study, we demonstrate that SNL-induced CaV3.2 upregulation in the spinal cord and DRG was attenuated by intrathecal infusion of mibefradil or ethosuximide. No obvious neurotoxicity effects were observed in all the tested groups. Our data suggest that continuous intrathecal infusion of TCC blockers may be considered as a promising alternative for the treatment of nerve injury-induced pain.
authors.affiliation: Department of Anesthesiology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Sheng-Jie
authors.initials: SJ
authors.lastname: Shiue
authors.affiliation: Department of Anesthesiology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, New Taipei City, Taiwan.
authors.forename: Chi-Hsu
authors.initials: CH
authors.lastname: Wang
authors.affiliation: Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Department of Pathology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Tao-Yeuan
authors.initials: TY
authors.lastname: Wang
authors.affiliation: Department of Anesthesiology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, New Taipei City, Taiwan. Electronic address: jkcheng@usa.net.
authors.forename: Jen-Kun
authors.initials: JK
authors.lastname: Cheng
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000008:administration & dosage*; D020747:Calcium Channels, T-Type / Q000502:physiology*; D005013:Ethosuximide / Q000008:administration & dosage / Q000633:toxicity; D008297:Male; D020748:Mibefradil / Q000008:administration & dosage / Q000633:toxicity; D009437:Neuralgia / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C509958:Cacna1h protein, rat; D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D020748:Mibefradil; D005013:Ethosuximide
keywords: Ca(V)3.2; T-type calcium channel; intrathecal; neuropathic pain; neurotoxicity