Intracellular calcium store filling by an L-type calcium current in the basolateral amygdala at subthreshold membrane potentials

J Physiol. 2005 Jan 15;562(Pt 2):439-53. doi: 10.1113/jphysiol.2004.076711. Epub 2004 Nov 18.


The long-term changes that underlie learning and memory are activated by rises in intracellular Ca2+ that activate a number of signalling pathways and trigger changes in gene transcription. Ca2+ rises due to influx via L-type voltage-dependent Ca2+ channels (L-VDCCs) and release from intracellular Ca2+ stores have been consistently implicated in the biochemical cascades that underlie the final changes in memory formation. Here, we show that pyramidal neurones in the basolateral amygdala express an L-VDCC that is active at resting membrane potentials. Subthreshold depolarization of neurones either by current injection or summating synaptic potentials led to a sustained rise in cytosolic Ca2+ that was blocked by the dihydropyridine nicardipine. Activation of metabotropic receptors released Ca2+ from intracellular Ca2+ stores. At hyperpolarized potentials, metabotropic-evoked store release ran down with repeated stimulation. Depolarization of cells to -50 mV, or maintaining them at the resting membrane potential, restored release from intracellular Ca2+ stores, an effect that was blocked by nicardipine. These results show that Ca2+ influx via a low-voltage-activated L-type Ca2+ current refills inositol 1,4,5-trisphosphate (IP(3))-sensitive intracellular Ca2+ stores, and maintains Ca2+ release and wave generation by metabotropic receptor activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Amygdala / drug effects
  • Amygdala / metabolism
  • Amygdala / physiology*
  • Animals
  • Calcium / metabolism*
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels, L-Type / drug effects
  • Calcium Channels, L-Type / metabolism*
  • In Vitro Techniques
  • Inositol 1,4,5-Trisphosphate / physiology
  • Kinetics
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Microscopy, Confocal
  • Microscopy, Fluorescence
  • Neuronal Plasticity / drug effects
  • Neuronal Plasticity / physiology
  • Rats
  • Synapses / drug effects
  • Synapses / physiology
  • omega-Conotoxin GVIA / pharmacology


  • Calcium Channel Blockers
  • Calcium Channels, L-Type
  • Inositol 1,4,5-Trisphosphate
  • omega-Conotoxin GVIA
  • Calcium