Effects of GABA on CA3 pyramidal cell dendrites in rabbit hippocampal slices

Damir Janigro, Philip A Schwartzkroin

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Using the in vitro rabbit hippocampal slice preparation, we have investigated the effects of γ-aminobutyric acid (GABA) iontophoresis on CA3 pyramidal cell dendrites. The predominant response (70% of the cells tested) was hyperpolarization associated with a 30% decrease in cell input resistance (Rin). These hyperpolarizations displayed a very pronounced voltage dependency: they were decreased by cell depolarization and flattered by hyperpolarization. Bicuculline methiodide (BMI, 50 μM) did not abolish this response, nor did intracellular iontophoresis of chloride ions. In 5% of the cells, and additional hyperpolarization was obtained with longer ejection times; it reversed close to the reversal potential of the early component of the IPSP. In 25% of the cells, dendritic GABA application produced a depolarization. This response was reversed with cell membrane depolarization and was associated with a large (80%) decrease in Rin. The depolarizations were abolished by BMI (50 μM) and greatly increased by increasing the intracellular chloride concentration. None of the responses to GABA were affected by blockade of synaptic transmission. We conclude that the predominant response of CA3 pyramidal cell dendrites to GABA application is a hyperpolarization mediated by GABAB receptors and probably carried by potassium ions. The depolarizing responses are mediated via GABAA receptors and depend on an increase in chloride permeability.

Original languageEnglish (US)
Pages (from-to)265-274
Number of pages10
JournalBrain Research
Volume453
Issue number1-2
DOIs
StatePublished - Jun 21 1988
Externally publishedYes

Keywords

  • CA3
  • Dendritic inhibition
  • GABA receptor
  • Hippocampal slice
  • Pyramidal cell
  • γ-Aminobutyric acid

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

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