Characterization of heterotopic cell clusters in the hippocampus of rats exposed to methylazoxymethanol in utero

Scott C. Baraban, H. Jurgen Wenzel, Daryl W. Hochman, Philip A Schwartzkroin

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

Cortical disorganization represents one of the major clinical findings in many children with medically intractable epilepsy. To study the relationship between seizure propensity and abnormal cortical structure, we have begun to characterize an animal model exhibiting aberrant neuronal clusters (heterotopia) and disruption of cortical lamination. In this model, exposing rats in utero to the DNA methylating agent methylazoxymethanol acetate (MAM; embryonic day 15) disrupts the sequence of normal brain development. In MAM-exposed rats, cells in hippocampal heterotopia exhibit neuronal morphology and do not stain with immunohistochemical markers for glia. In hippocampal slices from MAM-exposed animals, extracellular field recordings within heterotopia suggest that these dysplastic cell clusters make synaptic connections locally (i.e. within the CA1 hippocampal subregion) and also make aberrant synaptic contact with neocortical cells. Slice perfusion with bicuculline or 4-aminopyridine leads to epileptiform activity in dysplastic cell clusters that can occur independent of input from CA3. Taken together, our findings suggest that neurons within regions of abnormal hippocampal organization are capable of independent epileptiform activity generation, and can project abnormal discharge to a broad area of neocortex, as well as hippocampus. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)87-102
Number of pages16
JournalEpilepsy Research
Volume39
Issue number2
DOIs
StatePublished - 2000
Externally publishedYes

Keywords

  • Dysplasia
  • Electrophysiology
  • Hippocampus
  • Pediatric epilepsy

ASJC Scopus subject areas

  • Clinical Neurology
  • Pediatrics, Perinatology, and Child Health
  • Neurology

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