Pflügers Archiv - European Journal of Physiology

, Volume 467, Issue 4, pp 737–752

Compromised maturation of GABAergic inhibition underlies abnormal network activity in the hippocampus of epileptic Ca2+ channel mutant mice, tottering

  • Akito Nakao
  • Takafumi Miki
  • Ken Shimono
  • Hiroaki Oka
  • Tomohiro Numata
  • Shigeki Kiyonaka
  • Kaori Matsushita
  • Hiroo Ogura
  • Tetsuhiro Niidome
  • Jeffrey L. Noebels
  • Minoru Wakamori
  • Keiji Imoto
  • Yasuo Mori
Ion channels, receptors and transporters

DOI: 10.1007/s00424-014-1555-6

Cite this article as:
Nakao, A., Miki, T., Shimono, K. et al. Pflugers Arch - Eur J Physiol (2015) 467: 737. doi:10.1007/s00424-014-1555-6
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Abstract

Cholinergically induced network activity is a useful analogue of theta rhythms involved in memory processing or epileptiform activity in the hippocampus, providing a powerful tool to elucidate the mechanisms of synchrony in neuronal networks. In absence epilepsy, although its association with cognitive impairments has been reported, the mechanisms underlying hippocampal synchrony remain poorly investigated. Here we simultaneously recorded electrical activities from 64 sites in hippocampal slices of CaV2.1 Ca2+ channel mutant tottering (tg) mice, a well-established mouse model of spontaneous absence epilepsy, to analyze the spatiotemporal pattern of cholinergically induced hippocampal network activity. The cholinergic agonist carbachol induced oscillatory discharges originating from the CA3 region. In tg/tg mice, this hippocampal network activity was characterized by enhanced occupancy of discharges of relatively high frequency (6–10 Hz) compared to the wild type. Pharmacological analyses of slices, patch clamp electrophysiological characterization of isolated neurons, and altered patterns of hippocampal GABAA receptor subunit and Cl transporter messenger RNA (mRNA) transcript levels revealed that this abnormality is attributable to a developmental retardation of GABAergic inhibition caused by immature intracellular Cl regulation. These results suggest that the inherited CaV2.1 Ca2+ channel mutation leads to developmental abnormalities in Cl transporter expression and GABAA receptor compositions in hippocampal neurons and that compromised maturation of GABAergic inhibition contributes to the abnormal synchrony in the hippocampus of tg absence epileptic mice.

Keywords

CaV2.1 Ca2+ channeltottering miceAbsence epilepsyHippocampal network activityGABAergic maturationCl homeostasis

Supplementary material

424_2014_1555_MOESM1_ESM.pdf (735 kb)
ESM 1(PDF 734 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Akito Nakao
    • 1
  • Takafumi Miki
    • 1
  • Ken Shimono
    • 4
  • Hiroaki Oka
    • 4
  • Tomohiro Numata
    • 1
    • 2
  • Shigeki Kiyonaka
    • 1
    • 2
    • 3
  • Kaori Matsushita
    • 5
  • Hiroo Ogura
    • 6
  • Tetsuhiro Niidome
    • 7
  • Jeffrey L. Noebels
    • 8
  • Minoru Wakamori
    • 9
  • Keiji Imoto
    • 5
  • Yasuo Mori
    • 1
    • 2
    • 3
  1. 1.Department of Synthetic Chemistry and Biological Chemistry, Graduate School of EngineeringKyoto UniversityKyotoJapan
  2. 2.Department of Technology and Ecology, Hall of Global Environmental ResearchKyoto UniversityKyotoJapan
  3. 3.Core Research for Evolution Science and TechnologyJapan Science and Technology AgencyChiyoda-kuJapan
  4. 4.Bioscience Technology Development OfficePanasonic CorporationKyotoJapan
  5. 5.Division of Neural Signaling, Department of Information PhysiologyNational Institute for Physiological SciencesMyodaijiJapan
  6. 6.Product Creation HeadquartersEisai Co., Ltd.TokyoJapan
  7. 7.Neuroscience Product Creation UnitEisai LimitedHatfieldUK
  8. 8.Department of NeurologyBaylor College of MedicineHoustonUSA
  9. 9.Department of Oral Biology, Graduate School of DentistryTohoku UniversitySendaiJapan
  10. 10.Department of Neurophysiology, Faculty of Life and Medical SciencesDoshisha UniversityKyotanabeJapan