Excitatory modulation in the cochlear nucleus through group I metabotropic glutamate receptor activation

J Neurosci. 2011 May 18;31(20):7450-5. doi: 10.1523/JNEUROSCI.1193-11.2011.


Activation of group I metabotropic glutamate receptors (mGluRs) has been suggested to modulate development of auditory neurons. However, the acute effects of mGluR activation on physiological response properties are unclear. To address this, we studied the effects of mGluRs in bushy cells (BCs) of the mammalian anteroventral cochlear nucleus (AVCN). Activation of mGluRs with dihydroxyphenylglycine (DHPG) caused depolarization of BCs in mice as old as P42, but did not affect neurotransmitter release by presynaptic auditory nerve (AN) fibers. Application of mGluR antagonists indicated that mGluRs are tonically active, and are highly sensitive to small elevations in ambient glutamate by the glutamate reuptake blocker threo-β-benzyloxyaspartic acid (TBOA). mGluR-mediated depolarization enhanced the firing probability in response to AN stimulation, and reduced the latency and jitter. Furthermore, excitation through postsynaptic mGluRs can significantly counterbalance the inhibitory effects of presynaptic GABA(B) receptors. Thus, interaction between these two modulatory pathways may provide additional flexibility for fine-tuning the BC relay.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cochlear Nucleus / drug effects
  • Cochlear Nucleus / metabolism*
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology*
  • Female
  • Male
  • Mice
  • Mice, Inbred CBA
  • Neurotransmitter Agents / metabolism
  • Presynaptic Terminals / drug effects
  • Presynaptic Terminals / metabolism
  • Receptors, Metabotropic Glutamate / agonists
  • Receptors, Metabotropic Glutamate / antagonists & inhibitors
  • Receptors, Metabotropic Glutamate / metabolism*


  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Neurotransmitter Agents
  • Receptors, Metabotropic Glutamate
  • metabotropic glutamate receptor type 1