Cell type dependence and variability in the short-term plasticity of EPSCs in identified mouse hippocampal interneurones

J Physiol. 2002 Jul 1;542(Pt 1):193-210. doi: 10.1113/jphysiol.2002.020024.

Abstract

Synapses exhibit different short-term plasticity patterns and this behaviour influences information processing in neuronal networks. We tested how the short-term plasticity of excitatory postsynaptic currents (EPSCs) depends on the postsynaptic cell type, identified by axonal arborizations and molecular markers in the hippocampal CA1 area. Three distinct types of short-term synaptic behaviour (facilitating, depressing and combined facilitating-depressing) were defined by fitting a dynamic neurotransmission model to the data. Approximately 75 % of the oriens-lacunosum-moleculare (O-LM) interneurones received facilitating EPSCs, but in three of 12 O-LM cells EPSCs also showed significant depression. Over 90 % of the O-LM cells were immunopositive for somatostatin and mGluR1alpha and all tested cells were decorated by strongly mGluR7a positive axon terminals. Responses in eight of 12 basket cells were described well with a model involving only depression, but the other cells displayed combined facilitating-depressing EPSCs. No apparent difference was found between the plasticity of EPSCs in cholecystokinin- or parvalbumin-containing basket cells. In oriens-bistratified cells (O-Bi), two of nine cells showed facilitating EPSCs, another two depressing, and the remaining five cells combined facilitating-depressing EPSCs. Seven of 10 cells tested for somatostatin were immunopositive, but mGluR1alpha was detectable only in two of 11 tested cells. Furthermore, most O-Bi cells projected to the CA3 area and the subiculum, as well as outside the hippocampal formation. Postsynaptic responses to action potentials recorded in vivo from a CA1 place cell were modelled, and revealed great differences between and within cell types. Our results demonstrate that the short-term plasticity of EPSCs is cell type dependent, but with significant heterogeneity within all three interneurone populations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / physiology
  • Calcium-Binding Proteins / metabolism
  • Dendrites / physiology
  • Excitatory Postsynaptic Potentials / physiology*
  • Hippocampus / chemistry
  • Hippocampus / cytology*
  • Hippocampus / physiology*
  • In Vitro Techniques
  • Interneurons / chemistry
  • Interneurons / physiology*
  • Male
  • Membrane Potentials / physiology
  • Mice
  • Mice, Inbred C57BL
  • Models, Biological
  • Nerve Net / cytology
  • Nerve Net / physiology
  • Neuronal Plasticity / physiology*
  • Neuropeptides / metabolism
  • Patch-Clamp Techniques
  • Receptors, Metabotropic Glutamate / metabolism

Substances

  • Calcium-Binding Proteins
  • Neuropeptides
  • Receptors, Metabotropic Glutamate