title: The antiepileptic medications carbamazepine and phenytoin inhibit native sodium currents in murine osteoblasts.
abstract: Fracture risk is a serious comorbidity in epilepsy and may relate to the use of antiepileptic drugs (AEDs). Many AEDs inhibit ion channel function, and the expression of these channels in osteoblasts raises the question of whether altered bone signaling increases bone fragility. We aimed to confirm the expression of voltage-gated sodium (NaV ) channels in mouse osteoblasts, and to investigate the action of carbamazepine and phenytoin on NaV channels.
  
  
  
  Immunocytochemistry was performed on primary calvarial osteoblasts extracted from neonatal C57BL/6J mice and additional RNA sequencing (RNASeq) was included to confirm expression of NaV . Whole-cell patch-clamp recordings were made to identify the native currents expressed and to assess the actions of carbamazepine (50 μm) or phenytoin (50 μm).
  
  
  
  NaV expression was demonstrated with immunocytochemistry, RNA sequencing, and functionally, with demonstration of robust tetrodotoxin-sensitive and voltage-activated inward currents. Application of carbamazepine or phenytoin resulted in significant inhibition of current amplitude for carbamazepine (31.6 ± 5.9%, n = 9; p < 0.001), and for phenytoin (35.5 ± 6.9%, n = 7; p < 0.001).
  
  
  
  Mouse osteoblasts express NaV , and native NaV currents are blocked by carbamazepine and phenytoin, supporting our hypothesis that AEDs can directly influence osteoblast function and potentially affect bone strength.
authors.affiliation: The Department of Medicine, Melbourne Brain Centre at The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.|The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.|Department of Neurology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.|Academic Centre, Ormond College, Parkville, Victoria, Australia.|Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Petty
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Milligan
authors.affiliation: The Department of Medicine, Melbourne Brain Centre at The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Marian
authors.initials: M
authors.lastname: Todaro
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.
authors.forename: Kay L
authors.initials: KL
authors.lastname: Richards
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Pamuditha K
authors.initials: PK
authors.lastname: Kularathna
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Pagel
authors.affiliation: The Department of Medicine, Melbourne Brain Centre at The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.|Department of Neurology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.|Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Chris R
authors.initials: CR
authors.lastname: French
authors.affiliation: Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Elisa L
authors.initials: EL
authors.lastname: Hill-Yardin
authors.affiliation: The Department of Medicine, Melbourne Brain Centre at The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.|Department of Neurology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.|Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Terence J
authors.initials: TJ
authors.lastname: O'Brien
authors.affiliation: Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.|Bone and Mineral Medicine, The Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: John D
authors.initials: JD
authors.lastname: Wark
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Eleanor J
authors.initials: EJ
authors.lastname: Mackie
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Petrou
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000927:Anticonvulsants / Q000494:pharmacology*; D002220:Carbamazepine / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005786:Gene Expression Regulation / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010672:Phenytoin / Q000494:pharmacology*; D012333:RNA, Messenger; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D000927:Anticonvulsants; D012333:RNA, Messenger; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D002220:Carbamazepine; D013779:Tetrodotoxin; D010672:Phenytoin
keywords: Bone health; Electrophysiology; Epilepsy; Osteoblast; Voltage-gated sodium channel