Dendritic glutamate autoreceptors modulate signal processing in rat mitral cells

J Neurophysiol. 2001 Mar;85(3):1275-82. doi: 10.1152/jn.2001.85.3.1275.


It has been shown recently that in mitral cells of the rat olfactory bulb, N-methyl-D-aspartate (NMDA) autoreceptors are activated during mitral cell firing. Here we consider in more details the mechanisms of mitral cell self-excitation and its physiological relevance. We show that both ionotropic NMDA and non-NMDA autoreceptors are activated by glutamate released from primary and secondary dendrites. In contrast to non-NMDA autoreceptors, NMDA autoreceptors are almost exclusively located on secondary dendrites and their activation generates a large and sustained self-excitation. Both intracellularly evoked and miniature NMDA-R mediated synaptic potentials are blocked by intracellular bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA) and result from a calcium-dependent release of glutamate. Self-excitation can be produced by a single spike, and trains of spikes result in frequency facilitation. Thus activation of excitatory autoreceptors is a major function of action potentials backpropagating in mitral cell dendrites, which results in an immediate positive feedback counteracting recurrent inhibition and increasing the signal-to-noise ratio of olfactory inputs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Autoreceptors / metabolism*
  • Calcium Signaling / physiology
  • Dendrites / metabolism*
  • Electric Stimulation
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology
  • GABA-A Receptor Antagonists
  • Glutamic Acid / metabolism*
  • In Vitro Techniques
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology
  • Olfactory Bulb / cytology
  • Olfactory Bulb / metabolism*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, AMPA / antagonists & inhibitors
  • Receptors, AMPA / metabolism
  • Receptors, Metabotropic Glutamate / antagonists & inhibitors
  • Receptors, Metabotropic Glutamate / metabolism
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Signal Transduction / physiology*
  • Sodium / metabolism


  • Autoreceptors
  • Excitatory Amino Acid Antagonists
  • GABA-A Receptor Antagonists
  • Receptors, AMPA
  • Receptors, Metabotropic Glutamate
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • Sodium