In vitro ictogenesis and parahippocampal networks in a rodent model of temporal lobe epilepsy

Neurobiol Dis. 2010 Sep;39(3):372-80. doi: 10.1016/j.nbd.2010.05.003. Epub 2010 May 7.

Abstract

Temporal lobe epilepsy (TLE) is a chronic epileptic disorder involving the hippocampal formation. Details on the interactions between the hippocampus proper and parahippocampal networks during ictogenesis remain, however, unclear. In addition, recent findings have shown that epileptic limbic networks maintained in vitro are paradoxically less responsive than non-epileptic control (NEC) tissue to application of the convulsant drug 4-aminopyridine (4AP). Field potential recordings allowed us to establish here the effects of 4AP in brain slices obtained from NEC and pilocarpine-treated epileptic rats; these slices included the hippocampus and parahippocampal areas such as entorhinal and perirhinal cortices and the amygdala. First, we found that both types of tissue generate epileptiform discharges with similar electrographic characteristics. Further investigation showed that generation of robust ictal-like discharges in the epileptic rat tissue is (i) favored by decreased hippocampal output (ii) reinforced by EC-subiculum interactions and (iii) predominantly driven by amygdala networks. We propose that a functional switch to alternative synaptic routes may promote network hyperexcitability in the epileptic limbic system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Aminopyridine / pharmacology
  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Amygdala / drug effects
  • Amygdala / physiopathology*
  • Animals
  • Disease Models, Animal
  • Electrophysiology
  • Epilepsy, Temporal Lobe / chemically induced
  • Epilepsy, Temporal Lobe / physiopathology*
  • Hippocampus / drug effects
  • Hippocampus / physiopathology*
  • Male
  • Nerve Net / drug effects
  • Nerve Net / physiopathology*
  • Parahippocampal Gyrus / drug effects
  • Parahippocampal Gyrus / physiopathology*
  • Pilocarpine
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Pilocarpine
  • 4-Aminopyridine