Hilar somatostatin interneurons contribute to synchronized GABA activity in an in vitro epilepsy model

PLoS One. 2014 Jan 21;9(1):e86250. doi: 10.1371/journal.pone.0086250. eCollection 2014.

Abstract

Epilepsy is a disorder characterized by excessive synchronized neural activity. The hippocampus and surrounding temporal lobe structures appear particularly sensitive to epileptiform activity. Somatostatin (SST)-positive interneurons within the hilar region have been suggested to gate hippocampal activity, and therefore may play a crucial role in the dysregulation of hippocampal activity. In this study, we examined SST interneuron activity in the in vitro 4-aminopyridine (4-AP) model of epilepsy. We employed a multi-disciplinary approach, combining extracellular multi-electrode array (MEA) recordings with patch-clamp recordings and optical imaging using a genetically encoded calcium sensor. We observed that hilar SST interneurons are strongly synchronized during 4-AP-induced local field potentials (LFPs), as assayed by Ca(2+) imaging as well as juxtacellular or intracellular recording. SST interneurons were particularly responsive to GABA-mediated LFPs that occurred in the absence of ionotropic glutamatergic transmission. Our results present evidence that the extensive synchronized activity of SST-expressing interneurons contribute to the generation of GABAergic LFPs in an in vitro model of temporal lobe seizures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Aminopyridine / pharmacology
  • Action Potentials / drug effects
  • Animals
  • Calcium / metabolism
  • Epilepsy, Temporal Lobe / metabolism
  • Interneurons / drug effects
  • Interneurons / metabolism*
  • Mice
  • Somatostatin / metabolism*
  • gamma-Aminobutyric Acid / metabolism*

Substances

  • Somatostatin
  • gamma-Aminobutyric Acid
  • 4-Aminopyridine
  • Calcium

Grants and funding

SG was supported by a grant (GRK1123) funded by the German Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.