title: Seizure suppression by high frequency optogenetic stimulation using in vitro and in vivo animal models of epilepsy.
abstract: BACKGROUND
  Electrical high frequency stimulation (HFS) has been shown to suppress seizures. However, the mechanisms of seizure suppression remain unclear and techniques for blocking specific neuronal populations are required.
  
  
  OBJECTIVE
  The goal is to study the optical HFS protocol on seizures as well as the underlying mechanisms relevant to the HFS-mediated seizure suppression by using optogenetic methodology.
  
  
  METHODS
  Thy1-ChR2 transgenic mice were used in both vivo and in vitro experiments. Optical stimulation with pulse trains at 20 and 50 Hz was applied on the focus to determine its effects on in vivo seizure activity induced by 4-AP and recorded in the bilateral and ipsilateral-temporal hippocampal CA3 regions. In vitro methodology was then used to study the mechanisms of the in vivo suppression.
  
  
  RESULTS
  Optical HFS was able to generate 82.4% seizure suppression at 50 Hz with light power of 6.1 mW and 80.2% seizure suppression at 20 Hz with light power of 2.0 mW. The suppression percentage increased by increasing the light power and saturated when the power reached above-mentioned values. In vitro experimental results indicate that seizure suppression was mediated by activation of GABA receptors. Seizure suppression effect decreased with continued application but the suppression effect could be restored by intermittent stimulation.
  
  
  CONCLUSIONS
  This study shows that optical stimulation at high frequency targeting an excitatory opsin has potential therapeutic application for fast control of an epileptic focus. Furthermore, electrophysiological observations of extracellular and intracellular signals revealed that GABAergic neurotransmission activated by optical stimulation was responsible for the suppression.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Chia-Chu
authors.initials: CC
authors.lastname: Chiang
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Ladas
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Gonzalez-Reyes
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. Electronic address: dominique.durand@case.edu.
authors.forename: Dominique M
authors.initials: DM
authors.lastname: Durand
mesh_terms: D015761:4-Aminopyridine; D000818:Animals; D056654:CA3 Region, Hippocampal / Q000502:physiology*; D004195:Disease Models, Animal; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000502:physiology; D062308:Optogenetics; D010852:Picrotoxin / Q000494:pharmacology; D018079:Receptors, GABA / Q000502:physiology; D012640:Seizures / Q000139:chemically induced / Q000628:therapy*
chemical_list: D015761:4-Aminopyridine; D018756:GABA Antagonists; D010852:Picrotoxin; D018079:Receptors, GABA
keywords: 4-AP; High frequency stimulation; Hippocampus; Optogenetics; Seizure suppression
references.citation: Epilepsia. 1999 Oct;40(10):1378-83
references.pmid: 10528932
references.citation: Exp Neurol. 2015 Jul;269:120-32
references.pmid: 25863022
references.citation: J Neurosci. 1995 Oct;15(10):6651-65
references.pmid: 7472426
references.citation: J Physiol. 1999 Sep 15;519 Pt 3:693-712
references.pmid: 10457084
references.citation: J Physiol. 1980 Aug;305:279-96
references.pmid: 7441554
references.citation: Neuropharmacology. 2013 Jun;69:89-95
references.pmid: 22698957
references.citation: J Comp Neurol. 1994 Jan 8;339(2):181-208
references.pmid: 8300905
references.citation: J Neurophysiol. 2001 Apr;85(4):1351-6
references.pmid: 11287459
references.citation: Nat Commun. 2013;4:1376
references.pmid: 23340416
references.citation: Epilepsy Res. 2010 Feb;88(2-3):239-46
references.pmid: 20044240
references.citation: Proc Natl Acad Sci U S A. 2005 Sep 13;102(37):13295-300
references.pmid: 16141320
references.citation: J Neurosci. 2012 Feb 15;32(7):2499-512
references.pmid: 22396423
references.citation: Neural Plast. 2011;2011:728395
references.pmid: 21766044
references.citation: J Physiol. 2003 Mar 1;547(Pt 2):427-34
references.pmid: 12562909
references.citation: Nature. 2007 Apr 5;446(7136):633-9
references.pmid: 17410168
references.citation: Epilepsia. 2004 Jun;45(6):695-714
references.pmid: 15144438
references.citation: Int J Neural Syst. 2011 Apr;21(2):151-62
references.pmid: 21442778
references.citation: Proc Natl Acad Sci U S A. 2003 Nov 25;100(24):13940-5
references.pmid: 14615590
references.citation: Proc Natl Acad Sci U S A. 2009 Jul 21;106(29):12162-7
references.pmid: 19581573
references.citation: Hippocampus. 2012 Jan;22(1):98-105
references.pmid: 20882549
references.citation: Sci Transl Med. 2012 Nov 21;4(161):161ra152
references.pmid: 23147003
references.citation: Br J Pharmacol. 1998 Jul;124(6):1075-82
references.pmid: 9720776
references.citation: J Biol Chem. 1982 Sep 10;257(17):10306-13
references.pmid: 7107607
references.citation: Neuron. 2003 Sep 11;39(6):961-73
references.pmid: 12971896
references.citation: Neuron. 2011 Jul 14;71(1):9-34
references.pmid: 21745635
references.citation: J Comp Neurol. 2001 Dec 24;441(4):324-44
references.pmid: 11745653
references.citation: Nat Protoc. 2010 Feb;5(2):247-54
references.pmid: 20134425
references.citation: J Physiol. 1995 Mar 15;483 ( Pt 3):597-611
references.pmid: 7776246
references.citation: J Neurophysiol. 2003 Sep;90(3):1983-95
references.pmid: 12750426
references.citation: Brain Stimul. 2013 Mar;6(2):180-9
references.pmid: 22621942
references.citation: Neuropharmacology. 2011 Sep;61(4):807-14
references.pmid: 21645533
references.citation: N Engl J Med. 2003 Sep 25;349(13):1257-66
references.pmid: 14507951
references.citation: J Neurosci. 2014 Feb 26;34(9):3364-77
references.pmid: 24573293
references.citation: Neurology. 2006 May 23;66(10):1490-4
references.pmid: 16554495
references.citation: Nat Neurosci. 2005 Sep;8(9):1263-8
references.pmid: 16116447
references.citation: J Neurophysiol. 2004 Apr;91(4):1457-69
references.pmid: 14668299
references.citation: J Neurophysiol. 2007 Mar;97(3):1887-902
references.pmid: 17151229
references.citation: Nat Neurosci. 2012 Jun 24;15(8):1102-4
references.pmid: 22729174
references.citation: Neuron. 2007 Apr 19;54(2):205-18
references.pmid: 17442243
references.citation: Neurobiol Dis. 2014 May;65:133-41
references.pmid: 24491965
references.citation: Fiziol Zh (1994). 2008;54(5):40-5
references.pmid: 19058511
references.citation: J Neurophysiol. 2006 Jun;95(6):3948-54
references.pmid: 16554499
references.citation: Epilepsia. 2007 Oct;48(10):1895-903
references.pmid: 17634064
references.citation: J Neurophysiol. 1989 Mar;61(3):512-23
references.pmid: 2709097
references.citation: Nat Neurosci. 2013 Jan;16(1):64-70
references.pmid: 23143518
references.citation: Epilepsia. 2007 Aug;48(8):1551-60
references.pmid: 17726798
references.citation: Nature. 1979 Sep 27;281(5729):315-7
references.pmid: 551280