Creation of AMPA-silent synapses in the neonatal hippocampus.

• In the developing brain, many glutamate synapses have been found to transmit only NMDA receptor-mediated signaling, that is, they are AMPA-silent. This result has been taken to suggest that glutamate synapses are initially AMPA-silent when they are formed, and that AMPA signaling is acquired through activity-dependent synaptic plasticity. The present study on CA3-CA1 synapses in the hippocampus of the neonatal rat suggests that AMPA-silent synapses are created through a form of activity-dependent silencing of AMPA signaling. We found that AMPA signaling, but not NMDA signaling, could be very rapidly silenced by presynaptic electrical stimulation at frequencies commonly used to probe synaptic function (0.05-1 Hz). Although this AMPA silencing required a rise in postsynaptic Ca(2+), it did not require activation of NMDA receptors, metabotropic glutamate receptors or voltage-gated calcium channels. The AMPA silencing, possibly explained by a removal of postsynaptic AMPA receptors, could subsequently be reversed by paired presynaptic and postsynaptic activity.

Nyckelord

Animals

Animals

Newborn

Calcium Signaling

drug effects

physiology

Cell Differentiation

drug effects

physiology

Cyclic AMP-Dependent Protein Kinases

antagonists & inhibitors

metabolism

Electric Stimulation

Enzyme Inhibitors

pharmacology

Excitatory Amino Acid Antagonists

Excitatory Postsynaptic Potentials

drug effects

physiology

Glutamic Acid

metabolism

Hippocampus

cytology

growth & development

metabolism

Neuronal Plasticity

drug effects

physiology

Presynaptic Terminals

drug effects

metabolism

Rats

Rats

Wistar

Receptors

AMPA

drug effects

metabolism

Receptors

N-Methyl-D-Aspartate

drug effects

metabolism

Signal Transduction

drug effects

physiology

Synapses

drug effects

metabolism

Synaptic Membranes

drug effects

metabolism

Synaptic Transmission

drug effects

physiology

Synaptic Vesicles

drug effects

metabolism

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