Developmental Changes in Calcium Channel Types Mediating Synaptic Transmission in Rat Auditory Brainstem

J Physiol. 1998 Jun 1;509 ( Pt 2)(Pt 2):419-23. doi: 10.1111/j.1469-7793.1998.419bn.x.

Abstract

1. Calcium channel blockers were tested on excitatory postsynaptic currents (EPSCs) at the synapse formed by the calyx of Held on the principal cells in the medial nucleus of trapezoid body (MNTB) in brainstem slices of 4- to 14-day-old rats. 2. At postnatal day 4-9 (P4-9), EPSCs were irreversibly suppressed by the P/Q-type Ca2+ channel blocker omega-agatoxin-IVA (omega-Aga-IVA, 200 nM) and also by the N-type Ca2+ channel blocker omega-conotoxin GVIA (omega-CgTx, 2 microM). A small fraction of EPSCs was resistant to both toxins but abolished by Cd2+ (100 microM). 3. After P7, the omega-CgTx-sensitive EPSC fraction diminished and eventually disappeared after P10. Concomitantly the fraction insensitive to both toxins decreased and became undetectable after P10. 4. In contrast, the omega-Aga-IVA-sensitive EPSC fraction increased with development and became predominant after P10. All through the developmental period examined, the L-type Ca2+ channel blocker nicardipine (10 microM) had no effect. 5. We conclude that presynaptic Ca2+ channel types triggering transmitter release undergo developmental switching during the early postnatal period.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / physiology
  • Animals
  • Brain Stem / growth & development
  • Brain Stem / physiology*
  • Cadmium / pharmacology
  • Calcium Channel Blockers / pharmacology*
  • Calcium Channels / biosynthesis*
  • Calcium Channels / classification
  • Calcium Channels / physiology
  • Evoked Potentials / drug effects
  • Evoked Potentials / physiology
  • Gene Expression Regulation, Developmental*
  • In Vitro Techniques
  • Olivary Nucleus / growth & development
  • Olivary Nucleus / physiology*
  • Peptides / pharmacology
  • Rats
  • Rats, Wistar
  • Spider Venoms / pharmacology
  • Synapses / drug effects
  • Synapses / physiology
  • omega-Agatoxin IVA
  • omega-Conotoxin GVIA

Substances

  • Calcium Channel Blockers
  • Calcium Channels
  • Peptides
  • Spider Venoms
  • omega-Agatoxin IVA
  • Cadmium
  • omega-Conotoxin GVIA