Postsynaptic elevation of calcium induces persistent depression of developing neuromuscular synapses

Neuron. 1996 Apr;16(4):745-54. doi: 10.1016/s0896-6273(00)80095-1.


Synaptic activity is known to modulate neuronal connectivity in the nervous system. At developing Xenopus neuromuscular synapses in culture, repetitive postsynaptic application of ACh near the synapse leads to immediate and persistent synaptic depression, which was shown to be caused by reduction of presynaptic evoked transmitter release. However, little depression was found when ACh was applied to the muscle 20 microns or further from the synapse. Fluorescence imaging of cytosolic Ca2+ ([Ca2+]i) showed that each ACh pulse induced a transient elevation of myocyte [Ca2+]i that spread approximately 20 microns. Local photoactivated release of Ca2+ from the caged Ca2+ chelators nitr-5 or nitrophen in the postsynaptic cell was sufficient to induce persistent synaptic depression. These results support a model in which localized Ca2+ influx into the postsynaptic myocyte initiates transsynaptic retrograde modulation of presynaptic secretion mechanisms.

Publication types

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

MeSH terms

  • Acetylcholine / administration & dosage
  • Acetylcholine / pharmacology
  • Animals
  • Calcium / metabolism*
  • Cells, Cultured
  • Coculture Techniques
  • Electric Conductivity
  • Iontophoresis
  • Microscopy, Fluorescence
  • Motor Endplate / physiology
  • Muscles / cytology
  • Muscles / embryology
  • Muscles / metabolism
  • Neuromuscular Junction / embryology*
  • Neuromuscular Junction / physiology
  • Photolysis
  • Ultraviolet Rays
  • Xenopus / embryology


  • Acetylcholine
  • Calcium