Calcium/calmodulin-dependent kinase II and long-term potentiation enhance synaptic transmission by the same mechanism

Pierre Marie Lledo, Gregory O. Hjelmstad, Sucheta Mukherji, Thomas R. Soderling, Robert C. Malenka, Roger A. Nicoll

Research output: Contribution to journalArticlepeer-review

372 Scopus citations


Ca2+-sensitive kinases are thought to play a role in long-term potentiation (LTP). To test the involvement of Ca2+/calmodulin-dependent kinase II (CaM-K II), a truncated, constitutively active form of this kinase was directly injected into CA1 hippocampal pyramidal cells. Inclusion of CaM- K II in the recording pipette resulted in a gradual increase in the size of excitatory postsynaptic currents (EPSCs). No change in evoked responses occurred when the pipette contained heat-inactivated kinase. The effects of CaM-K II mimicked several features of LTP in that it caused a decreased incidence of synoptic failures, an increase in the size of spontaneous EPSCs, and an increase in the amplitude of responses to iontophoretically applied α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate. To determine whether the CaM-K II-induced enhancement and LTP share a common mechanism, occlusion experiments were carried out. The enhancing action of CaM-K II was greatly diminished by prior induction of LTP. In addition, following the increase in synaptic strength by CaM-K II, tetanic stimulation failed to evoke LTP. These findings indicate that CaM-K II alone is sufficient to augment synaptic strength and that this enhancement shares the same underlying mechanism as the enhancement observed with LTP.

Original languageEnglish (US)
Pages (from-to)11175-11179
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number24
StatePublished - Nov 21 1995


  • glutamate receptor
  • learning
  • synaptic plasticity

ASJC Scopus subject areas

  • General


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