Kinetics of GABAB receptor-mediated inhibition of calcium currents and excitatory synaptic transmission in hippocampal neurons in vitro

Neuron. 1994 Jan;12(1):97-107. doi: 10.1016/0896-6273(94)90155-4.


The time courses of the gamma-aminobutyric acid type B (GABAB) receptor-mediated inhibition of excitatory synaptic transmission and of action potential-evoked calcium currents were studied in hippocampal neurons in vitro with step-like changes of a saturating baclofen concentration. Inhibition mediated by postsynaptic GABAB receptors was excluded pharmacologically. Both presynaptic inhibition and reduction of calcium currents developed and declined exponentially with similar time constants of about 0.2 and 3 s, respectively. The close correlation of the time courses indicates that fast, G protein-mediated depression of voltage-gated calcium channels and thus direct reduction of the presynaptic calcium influx may contribute to the GABAB receptor-induced inhibition of excitatory synaptic transmission in hippocampal neurons in vitro.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Baclofen / pharmacology*
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Cells, Cultured
  • Electrophysiology / methods
  • Embryo, Mammalian
  • Evoked Potentials / drug effects
  • Evoked Potentials / physiology
  • GTP-Binding Proteins / metabolism
  • Hippocampus / physiology*
  • Kinetics
  • Neurons / physiology*
  • Quinoxalines / pharmacology*
  • Rats
  • Receptors, GABA-B / drug effects
  • Receptors, GABA-B / physiology*
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*


  • Calcium Channels
  • Quinoxalines
  • Receptors, GABA-B
  • FG 9041
  • GTP-Binding Proteins
  • Baclofen