Dissociation of the IPSP and response to GABA during spreading depression-like depolarizations in hippocampal slices

Damir Janigro, Philip A Schwartzkroin

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We have compared the sensitivity of CA1 and CA3 hippocampal pyramidal cells, in mature and immature tissue, to spreading depression-like depolarization episodes. Using hippocampal slices from rabbit, we have found that mature and immature tissue, and CA1 and CA3 neurons, were differentially prone to depolarization episodes, depending on the method used to produce the depolarization. CA1 region was generally more sensitive than CA3. Spontaneous and stimulus-evoked depolarizations were seen more frequently in immature tissue than in mature slices, but anoxia-induced depolarizations were much more likely to occur in mature tissue. Synaptic transmission and responses to somatic γ-aminobutyric acid (GABA) ejection were compared during anoxia-induced depolarizations in mature slices. The early component of the inhibitory postsynaptic potential (IPSP) normally had the same reversal potential as the GABA response. During anoxia-induced depolarization, both the drug response and the PSP were lost. Synaptic transmission generally disappeared before the response to exogenous GABA application; the GABA response reappeared before synaptic function was restored. During the recovery of resting potential (RMP) following depolarizatuion, the reversal potential of the early IPSP differed significantly from that of the GABA response; when the cell had recovered to RMP, the IPSP was depolarizing, whereas GABA application produced a 'normal' cell hyperpolarization. IPSPs and GABA-mediated responses attained their pre-depolarization form within a few minutes of RMP recovery. These observations suggest that, at least under special circumstances, the early component of the IPSP and GABA-mediated hyperpolarizations can be dissociated. Therefore, the early IPSP may be mediated by more complex mechanisms than a simple alteration in chloride conductance due to GABA-receptor interactions.

Original languageEnglish (US)
Pages (from-to)189-200
Number of pages12
JournalBrain Research
Volume404
Issue number1-2
DOIs
StatePublished - Feb 24 1987
Externally publishedYes

Keywords

  • Anoxia
  • Development
  • Hippocampal slice
  • Inhibitory postsynaptic potential (IPSP)
  • Pyramidal cell
  • Spreading depression
  • γ-Aminobutyric acid (GABA)

ASJC Scopus subject areas

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

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