title: Lamotrigine increases intracellular Ca(2+) levels and Ca(2+)/calmodulin-dependent kinase II activation in mouse dorsal root ganglion neurones.
abstract: OBJECTIVE
  Lamotrigine is a neuroprotective agent that is used clinically for the treatment of seizures and neuropathic pain. A significant volume of literature has reported that lamotrigine exerts analgesic effect by blocking Ca(2+) channels. However, little is known regarding the effect of lamotrigine on the intracellular Ca(2+) concentration ([Ca(2+)](i)). The aim of this study was to determine whether lamotrigine modulates [Ca(2+)](i) in sensory neurones.
  
  
  METHODS
  Lamotrigine-induced changes in [Ca(2+)](i) were measured in mouse dorsal root ganglion (DRG) neurones using the Ca(2+)-sensitive fluorescent indicator Fluo 3-AM and a confocal laser scanning microscope. Ca(2+)/calmodulin-dependent kinase II (CaMKII) activation was assessed by the fluorescence intensity using immunocytochemical procedures.
  
  
  RESULTS
  Treatment with 1, 10, 30 or 100 μM lamotrigine transiently increased [Ca(2+)](i) in DRG neurones in a dose-dependent manner. Treatment with 100 μM lamotrigine induced a significant (threefold) increase in the Ca(2+) peak in the presence or absence of extracellular Ca(2+). The lamotrigine-induced Ca(2+) increase was abolished or decreased by the treatment with a specific PLC inhibitor (U73122), IP3R antagonist (xestospongin C) or RyR antagonist (dantrolene). In some cells, treatment with 100 μM lamotrigine caused a transient Ca(2+) increase, and the Ca(2+) levels quickly fell to below the basal Ca(2+) level observed prior to lamotrigine application. The decrease in basal Ca(2+) levels was blocked by the treatment with a CaMKII inhibitor (KN93). Immunocytochemical analysis indicated that lamotrigine treatment increased the expression of phosphorylated CaMKII in DRG neurones.
  
  
  CONCLUSIONS
  Treatment with lamotrigine increased [Ca(2+)](i) apparently as a result of Ca(2+) release from intracellular stores and CaMKII activity.
authors.affiliation: Department of Rehabilitation Medicine and Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: E S
authors.initials: ES
authors.lastname: Lee
authors.forename: J H
authors.initials: JH
authors.lastname: Ryu
authors.forename: E-J
authors.initials: EJ
authors.lastname: Kim
authors.forename: G-T
authors.initials: GT
authors.lastname: Kim
authors.forename: Y-W
authors.initials: YW
authors.lastname: Cho
authors.forename: H-J
authors.initials: HJ
authors.lastname: Park
authors.forename: H-M
authors.initials: HM
authors.lastname: Tak
authors.forename: J
authors.initials: J
authors.lastname: Han
authors.forename: D
authors.initials: D
authors.lastname: Kang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005727:Ganglia, Spinal / Q000187:drug effects / Q000201:enzymology; D007150:Immunohistochemistry; D000077213:Lamotrigine; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D014227:Triazines / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D014227:Triazines; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium; D000077213:Lamotrigine