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Functional maturation of CA1 synapses involves activity-dependent loss of tonic kainate receptor-mediated inhibition

Sari E Lauri1, Aino Vesikansa, Mikael Segerstråle

  • 1Neuroscience Center and Department of Bio- and Environmental Sciences, P.O. Box 65 (Viikinkaari 1), 00014 University of Helsinki, Finland.

Neuron
|May 6, 2006
PubMed

Insights

During early development, a kainate receptor (KAR) depresses glutamate release at CA3-CA1 synapses. Activity-dependent down-regulation of KAR increases release probability, maturing excitatory transmission.

Area of Science:

  • Neuroscience
  • Synaptic Plasticity
  • Developmental Neurobiology

Background:

  • Excitatory synapses exhibit low efficacy in early development, partly due to low neurotransmitter release probability (Pr).
  • Mechanisms controlling activity-dependent maturation of presynaptic release remain largely unknown.

Purpose of the Study:

  • To investigate the role of kainate receptors (KARs) in regulating presynaptic release during early development.
  • To understand how activity-dependent changes in KAR function influence synaptic transmission properties.

Main Methods:

  • Electrophysiological recordings at CA3-CA1 synapses in developing networks.
  • Investigation of kainate receptor (KAR) activation by ambient glutamate.
  • Analysis of the impact of long-term potentiation (LTP) induction on KAR function and release probability (Pr).

Main Results:

  • A high-affinity, G protein-dependent KAR is tonically activated by ambient glutamate at early developmental CA3-CA1 synapses.
  • This KAR activation tonically depresses glutamate release, favoring transmission during high-frequency bursts.
  • Induction of LTP rapidly down-regulates tonic KAR activation, increasing Pr and altering synaptic dynamics.

Conclusions:

  • Activity-dependent loss of presynaptic KAR function is a key mechanism for the maturation of excitatory transmission from CA3 to CA1.
  • This process involves a shift in synaptic properties from burst-favoring to more sustained transmission.
  • Understanding these mechanisms is crucial for comprehending neural network development and function.

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