Extracellular Calcium Regulates Postsynaptic Efficacy through Group 1 Metabotropic Glutamate Receptors (2006)

Author(s): Hardingham NR, Bannister NJ, Read JCA, Fox KD, Hardingham GE, Jack JJB

    Abstract: Bursts of synaptic transmission are known to induce transient depletion of Ca2+ within the synaptic cleft. Although Ca2+ depletion has been shown to lower presynaptic release probability, effects on the postsynaptic cell have not been reported. In this study, we show that physiologically relevant reductions in extracellular Ca2+ lead to a decrease in synaptic strength between synaptically coupled layer 2/3 cortical pyramidal neurons. Using quantal analysis and mEPSP analysis, we demonstrate that a lowered extracellular Ca2+ produces a reduction in the postsynaptic quantal size in addition to its known effect on release probability. An elevated Mg2+ level can prevent this reduction in postsynaptic efficacy at subphysiological Ca2+ levels. We show that the calcium-dependent effect on postsynaptic quantal size is mediated by group 1 metabotropic glutamate receptors, acting via CaMKII (Ca2+/calmodulin-dependent protein kinase II) and PKC. Therefore, physiologically relevant changes in extracellular Ca2+ can regulate information transfer at cortical synapses via both presynaptic and postsynaptic mechanisms.

      • Date: 07-06-2006
      • Journal: Journal of Neuroscience
      • Volume: 26
      • Issue: 23
      • Pages: 6337-6345
      • Publisher: Society for Neuroscience
      • Publication type: Article
      • Bibliographic status: Published

      Professor Jennifer Read
      Professor of Vision Science