Synergistic release of Ca2+ from IP3-sensitive stores evoked by synaptic activation of mGluRs paired with backpropagating action potentials.
Increases in postsynaptic [Ca2+]i can result from Ca2+ entry through ligand-gated channels or voltage-gated Ca2+ channels, or through release from intracellular stores. Most attention has focused on entry through the N-methyl-D-aspartate (NMDA) receptor in causing [Ca2+]i increases since this pathway requires both presynaptic stimulation and postsynaptic depolarization, making it a central component in models of synaptic plasticity. Here, we report that repetitive synaptic activation of metabotropic glutamate receptors (mGluRs), paired with backpropagating action potentials, causes large, wave-like increases in [Ca2+]i predominantly in restricted regions of the proximal apical dendrites and soma of hippocampal CA1 pyramidal neurons. [Ca2+]i changes of several micromolars can be reached by regenerative release caused by the synergistic effect of mGluR-generated inositol 1,4,5-trisphosphate (IP3) and spike-evoked Ca2+ entry acting on the IP3 receptor.
Nakamura
T
T
Department of Physiology, New York Medical College, Valhalla 10595, USA.
Barbara
J G
JG
Nakamura
K
K
Ross
W N
WN
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004357:Drug Synergism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology*; D007425:Intracellular Membranes / Q000378:metabolism; D009994:Osmolar Concentration; D017966:Pyramidal Cells / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D018094:Receptors, Metabotropic Glutamate; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium