Cellular and network properties of the subiculum in the pilocarpine model of temporal lobe epilepsy

Andreas Knopp, Anatol Kivi, Christian Wozny, Uwe Heinemann, Joachim Behr

Research output: Contribution to journalArticle

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Abstract

The subiculum was recently shown to be crucially involved in the generation of interictal activity in human temporal lobe epilepsy. Using the pilocarpine model of epilepsy, this study examines the anatomical substrates for network hyperexcitability recorded in the subiculum. Regular- and burst-spiking subicular pyramidal cells were stained with fluorescence dyes and reconstructed to analyze seizure-induced alterations of the dendritic and axonal system. In control animals burst-spiking cells outnumbered regular-spiking cells by about two to one. Regular- and burst-spiking cells were characterized by extensive axonal branching and autapse-like contacts, suggesting a high intrinsic connectivity. In addition, subicular axons projecting to CA1 indicate a CA1-subiculum-CA1 circuit. In the subiculum of pilocarpine-treated rats we found an enhanced network excitability characterized by spontaneous rhythmic activity, polysynaptic responses, and all-or-none evoked bursts of action potentials. In pilocarpine-treated rats the subiculum showed cell loss of about 30%. The ratio of regular- and burst-spiking cells was practically inverse as compared to control preparations. A reduced arborization and spine density in the proximal part of the apical dendrites suggests a partial deafferentiation from CA1. In pilocarpine-treated rats no increased axonal outgrowth of pyramidal cells was observed. Hence, axonal sprouting of subicular pyramidal cells is not mandatory for the development of the pathological events. We suggest that pilocarpine-induced seizures cause an unmasking or strengthening of synaptic contacts within the recurrent subicular network.

LanguageEnglish
Pages476-88
Number of pages13
JournalJournal of Comparative Neurology
Volume483
Issue number4
DOIs
Publication statusPublished - 21 Mar 2005

Fingerprint

Pilocarpine
Temporal Lobe Epilepsy
Hippocampus
Pyramidal Cells
Seizures
Dendrites
Human Activities
Action Potentials
Axons
Epilepsy
Spine
Coloring Agents
Fluorescence

Keywords

  • subiculum
  • CA1
  • cellular
  • dendrites
  • axons
  • morphology
  • temporal lobe epilepsy
  • rats
  • networks
  • hippocampus
  • pilocarpine

Cite this

Knopp, Andreas ; Kivi, Anatol ; Wozny, Christian ; Heinemann, Uwe ; Behr, Joachim. / Cellular and network properties of the subiculum in the pilocarpine model of temporal lobe epilepsy. In: Journal of Comparative Neurology. 2005 ; Vol. 483, No. 4. pp. 476-88.
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Cellular and network properties of the subiculum in the pilocarpine model of temporal lobe epilepsy. / Knopp, Andreas; Kivi, Anatol; Wozny, Christian; Heinemann, Uwe; Behr, Joachim.

In: Journal of Comparative Neurology, Vol. 483, No. 4, 21.03.2005, p. 476-88.

Research output: Contribution to journalArticle

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T1 - Cellular and network properties of the subiculum in the pilocarpine model of temporal lobe epilepsy

AU - Knopp, Andreas

AU - Kivi, Anatol

AU - Wozny, Christian

AU - Heinemann, Uwe

AU - Behr, Joachim

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N2 - The subiculum was recently shown to be crucially involved in the generation of interictal activity in human temporal lobe epilepsy. Using the pilocarpine model of epilepsy, this study examines the anatomical substrates for network hyperexcitability recorded in the subiculum. Regular- and burst-spiking subicular pyramidal cells were stained with fluorescence dyes and reconstructed to analyze seizure-induced alterations of the dendritic and axonal system. In control animals burst-spiking cells outnumbered regular-spiking cells by about two to one. Regular- and burst-spiking cells were characterized by extensive axonal branching and autapse-like contacts, suggesting a high intrinsic connectivity. In addition, subicular axons projecting to CA1 indicate a CA1-subiculum-CA1 circuit. In the subiculum of pilocarpine-treated rats we found an enhanced network excitability characterized by spontaneous rhythmic activity, polysynaptic responses, and all-or-none evoked bursts of action potentials. In pilocarpine-treated rats the subiculum showed cell loss of about 30%. The ratio of regular- and burst-spiking cells was practically inverse as compared to control preparations. A reduced arborization and spine density in the proximal part of the apical dendrites suggests a partial deafferentiation from CA1. In pilocarpine-treated rats no increased axonal outgrowth of pyramidal cells was observed. Hence, axonal sprouting of subicular pyramidal cells is not mandatory for the development of the pathological events. We suggest that pilocarpine-induced seizures cause an unmasking or strengthening of synaptic contacts within the recurrent subicular network.

AB - The subiculum was recently shown to be crucially involved in the generation of interictal activity in human temporal lobe epilepsy. Using the pilocarpine model of epilepsy, this study examines the anatomical substrates for network hyperexcitability recorded in the subiculum. Regular- and burst-spiking subicular pyramidal cells were stained with fluorescence dyes and reconstructed to analyze seizure-induced alterations of the dendritic and axonal system. In control animals burst-spiking cells outnumbered regular-spiking cells by about two to one. Regular- and burst-spiking cells were characterized by extensive axonal branching and autapse-like contacts, suggesting a high intrinsic connectivity. In addition, subicular axons projecting to CA1 indicate a CA1-subiculum-CA1 circuit. In the subiculum of pilocarpine-treated rats we found an enhanced network excitability characterized by spontaneous rhythmic activity, polysynaptic responses, and all-or-none evoked bursts of action potentials. In pilocarpine-treated rats the subiculum showed cell loss of about 30%. The ratio of regular- and burst-spiking cells was practically inverse as compared to control preparations. A reduced arborization and spine density in the proximal part of the apical dendrites suggests a partial deafferentiation from CA1. In pilocarpine-treated rats no increased axonal outgrowth of pyramidal cells was observed. Hence, axonal sprouting of subicular pyramidal cells is not mandatory for the development of the pathological events. We suggest that pilocarpine-induced seizures cause an unmasking or strengthening of synaptic contacts within the recurrent subicular network.

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KW - CA1

KW - cellular

KW - dendrites

KW - axons

KW - morphology

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KW - rats

KW - networks

KW - hippocampus

KW - pilocarpine

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EP - 488

JO - Journal of Comparative Neurology

T2 - Journal of Comparative Neurology

JF - Journal of Comparative Neurology

SN - 0021-9967

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ER -