Protein kinase and phosphatase activity regulate the form of synaptic plasticity expressed

Synapse. 1996 Oct;24(2):97-103. doi: 10.1002/(SICI)1098-2396(199610)24:2<97::AID-SYN1>3.0.CO;2-9.


Long-term potentiation (LTP) and long-term depression (LTD) are calcium-dependent forms of synaptic plasticity observed in area CA1 of the hippocampus. Low-frequency tetani (1-5 Hz) activates protein phosphatases to induce LTD, whereas high-frequency tetani (> 25 Hz) activates protein kinases to induce LTP. A tetanus at an intermediate frequency (10 Hz), however, does not result in a change in synaptic efficacy [Dudek and Bear, (1992), Proc. Natl. Acad. Sci. USA, 89:4363-4367]. We hypothesized that the 10-Hz tetanus results in no long-term change in synaptic efficacy due to a balance of the activity of protein phosphatases and protein kinases. We manipulated protein kinase/phosphatase activity at a 10-Hz tetanus to test this hypothesis. A 10-Hz tetanus under normal conditions results in a transient depression which returns to baseline in 25 min. However, inhibiting kinase activity with the protein kinase inhibitor H-7, or decreasing extracellular calcium concentration, results in the 10-Hz tetanus, inducing LTD. Conversely, inhibiting phosphatase activity with the protein phosphatase inhibitor tautomycin, or increasing extracellular calcium concentration, results in the 10-Hz tetanus, inducing LTP. These results suggest that the relative balance of protein kinase and phosphatase activity (and/or the calcium levels activating them) determines the expression of specific forms of synaptic plasticity, and that these forms lie on a continuum.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / pharmacology
  • Neuronal Plasticity / physiology*
  • Phosphoric Monoester Hydrolases / physiology*
  • Protein Kinases / physiology*
  • Rats
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*


  • Protein Kinases
  • Phosphoric Monoester Hydrolases
  • Calcium