Non-calyceal excitatory inputs mediate low fidelity synaptic transmission in rat auditory brainstem slices

Eur J Neurosci. 2003 Nov;18(10):2899-902. doi: 10.1111/j.1460-9568.2003.03017.x.

Abstract

Principal neurons of the medial nucleus of the trapezoid body (MNTB) receive a synaptic input from a single giant calyx terminal that generates a fast-rising, large excitatory postsynaptic current (EPSC), each of which are supra-threshold for postsynaptic action potential generation. Here, we present evidence that MNTB principal neurons receive multiple excitatory synaptic inputs generating slow-rising, small EPSCs that are also capable of triggering postsynaptic action potentials but are of non-calyceal origin. Both calyceal and non-calyceal EPSCs are mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-d-aspartate (NMDA) receptor activation; however, the NMDA receptor-mediated response is proportionally larger at the non-calyceal synapses. Non-calyceal synapses generate action potentials in MNTB principal neurons with a longer latency and a lower reliability than the large calyceal input. They constitute an alternative low fidelity synaptic input to the fast and secure relay transmission via the calyx of Held synapse.

Publication types

  • Comparative Study

MeSH terms

  • Anesthetics, Local / pharmacology
  • Animals
  • Animals, Newborn
  • Auditory Pathways / physiology*
  • Brain Stem / cytology
  • Brain Stem / physiology*
  • Electric Stimulation
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology
  • In Vitro Techniques
  • Membrane Potentials / drug effects
  • Neurons / classification
  • Neurons / drug effects
  • Neurons / physiology*
  • Patch-Clamp Techniques / methods
  • Quinoxalines / pharmacology
  • Rats
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*
  • Tetrodotoxin / pharmacology
  • Time Factors
  • Valine / analogs & derivatives*
  • Valine / pharmacology
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology

Substances

  • Anesthetics, Local
  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Quinoxalines
  • 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
  • Tetrodotoxin
  • 2-amino-5-phosphopentanoic acid
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
  • Valine