Intracellular calcium dependence of transmitter release rates at a fast central synapse

Abstract

Calcium-triggered fusion of synaptic vesicles and neurotransmitter release are fundamental signalling steps in the central nervous system. It is generally assumed that fast transmitter release is triggered by elevations in intracellular calcium concentration ([Ca2+]i) to at least 100 µM near the sites of vesicle fusion1,2,3,4,5. For synapses in the central nervous system, however, there are no experimental estimates of this local [Ca2+]i signal. Here we show, by using calcium ion uncaging in the large synaptic terminals of the calyx of Held, that step-like elevations to only 10 µM [Ca2+] i induce fast transmitter release, which depletes around 80% of a pool of available vesicles in less than 3 ms. Kinetic analysis of transmitter release rates after [Ca2+]i steps revealed the rate constants for calcium binding and vesicle fusion. These show that transient (around 0.5 ms) local elevations of [Ca2+]i to peak values as low as 25 µM can account for transmitter release during single presynaptic action potentials. The calcium sensors for vesicle fusion are far from saturation at normal release probability. This non-saturation, and the high intracellular calcium cooperativity in triggering vesicle fusion, make fast synaptic transmission very sensitive to modulation by changes in local [Ca2+]i.

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Figure 1: Presynaptic [Ca2+] steps and postsynaptic detection of transmitter release.
Figure 2: [Ca2+]i elevations induced by flashes and presynaptic depolarizations release vesicles from a common pool.
Figure 3: Intracellular Ca2+ concentration dependence of transmitter release rates at the calyx of Held synapse.
Figure 4: The predicted local [Ca2+]i signal at an average Ca2+ sensor for vesicle fusion during single presynaptic action potentials.

References

  1. 1

    Adler, E. M., Augustine, G. J., Duffy, S. N. & Charlton, M. P. Alien intracellular calcium chelators attenuate neurotransmitter release at the squid giant synapse. J. Neurosci. 11, 1496–1507 (1991).

    CAS  Article  Google Scholar 

  2. 2

    Llinás, R., Sugimori, M. & Silver, R. B. Microdomains of high calcium concentration in a presynaptic terminal. Science 256, 677– 679 (1992).

    ADS  Article  Google Scholar 

  3. 3

    Yamada, W. M. & Zucker, R. S. Time course of transmitter release calculated from simulations of a calcium diffusion model. Biophys. J. 61, 671–682 ( 1992).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Heidelberger, R., Heinemann, C., Neher, E. & Matthews, G. Calcium dependence of the rate of exocytosis in a synaptic terminal. Nature 371, 513–515 (1994).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Roberts, W. M. Localization of calcium signals by a mobile calcium buffer in frog saccular hair cells. J. Neurosci. 14, 3246– 3262 (1994).

    CAS  Article  Google Scholar 

  6. 6

    Forsythe, I. D. Direct patch recording from identified presynaptic terminals mediating glutamatergic EPSCs in the rat CNS, in vitro. J. Physiol. 479, 381–387 (1994).

    Article  Google Scholar 

  7. 7

    Borst, J. G. G., Helmchen, F. & Sakmann, B. Pre- and postsynaptic whole-cell recordings in the medial nucleus of the trapezoid body of the rat. J. Physiol. 489, 825–840 (1995).

    CAS  Article  Google Scholar 

  8. 8

    Naraghi, M., Müller, T. H. & Neher, E. Two-dimensional determination of the cellular Ca2+ binding in bovine chromaffin cells. Biophys. J. 75, 1635–1647 (1998).

    CAS  Article  Google Scholar 

  9. 9

    Thomas, P., Wong, J. G. & Almers, W. Millisecond studies of secretion in single rat pituitary cells stimulated by flash photolysis of caged Ca2+. EMBO J. 12, 303–306 ( 1993).

    CAS  Article  Google Scholar 

  10. 10

    Heinemann, C., Chow, R. H., Neher, E. & Zucker, R. S. Kinetics of the secretory response in bovine chromaffin cells following flash photolysis of caged Ca2+. Biophys. J. 67, 2546–2557 (1994).

    ADS  CAS  Article  Google Scholar 

  11. 11

    Yamada, K. A. & Tang, C.-M. Benzothiazides inhibit rapid glutamate receptor desensitization and enhance glutamatergic synaptic currents. J. Neurosci. 13, 3904–3915 (1993).

    CAS  Article  Google Scholar 

  12. 12

    Trussell, L. O., Zhang, S. & Raman, I. M. Desensitization of AMPA receptors upon multiquantal neurotransmitter release. Neuron 10, 1185 –1196 (1993).

    CAS  Article  Google Scholar 

  13. 13

    Borst, J. G. G. & Sakmann, B. Calcium influx and transmitter release in a fast CNS synapse. Nature 383, 431–434 (1996).

    ADS  CAS  Article  Google Scholar 

  14. 14

    Schneggenburger, R., Meyer, A. C. & Neher, E. Released fraction and total size of a pool of immediately available transmitter quanta at a calyx synapse. Neuron 23, 399–409 (1999).

    CAS  Article  Google Scholar 

  15. 15

    van der Kloot, W. Estimating the timing of quantal releases during end-plate currents at the frog neuromuscular junction. J. Physiol. 402, 595–603 (1988).

    CAS  Article  Google Scholar 

  16. 16

    Diamond, J. S. & Jahr, C. E. Asynchronous release of synaptic vesicles determines the time course of the AMPA receptor-mediated EPSC. Neuron 15, 1097–1107 (1995).

    CAS  Article  Google Scholar 

  17. 17

    Wu, L. -G. & Borst, J. G. G. The reduced release probability of releasable vesicles during recovery from short-term synaptic depression. Neuron 23, 821–832 (1999).

    CAS  Article  Google Scholar 

  18. 18

    Dodge, F. A. & Rahamimoff, R. Co-operative action of calcium ions in transmitter release at the neuromuscular junction. J. Physiol. 193, 419–432 ( 1967).

    CAS  Article  Google Scholar 

  19. 19

    Landò, L. & Zucker, R. S. Ca2+ cooperativity in neurosecretion measured using photolabile Ca2+ chelators. J. Neurophysiol. 72, 825–830 (1994).

    Article  Google Scholar 

  20. 20

    Barnes-Davies, M. & Forsythe, I. D. Pre- and postsynaptic glutamate receptors at a giant excitatory synapse in rat auditory brainstem slices. J. Physiol. 488, 387– 406 (1995).

    CAS  Article  Google Scholar 

  21. 21

    Lagnado, L., Gomis, A. & Job, C. Continuous vesicle cycling in the synaptic terminal of retinal bipolar cells. Neuron 17, 957–967 (1996).

    CAS  Article  Google Scholar 

  22. 22

    Ohana, O. & Sakmann, B. Transmitter release modulation in nerve terminals of rat neocortical pyramidal cells by intracellular calcium buffers. J. Physiol. 513, 135– 148 (1998).

    CAS  Article  Google Scholar 

  23. 23

    Helmchen, F., Borst, J. G. G. & Sakmann, B. Calcium dynamics associated with a single action potential in a CNS presynaptic terminal. Biophys. J. 72, 1458–1471 (1997).

    ADS  CAS  Article  Google Scholar 

  24. 24

    Goda, Y. & Südhof, T. Calcium regulation of neurotransmitter release: reliably unreliable? Curr. Opin. Cell Biol. 9, 513–518 (1997).

    CAS  Article  Google Scholar 

  25. 25

    Wu, L. -G. & Saggau, P. Presynaptic inhibition of elicited neurotransmitter release. Trends Neurosci. 20, 204–212 (1997).

    CAS  Article  Google Scholar 

  26. 26

    Zucker, R. S. Calcium- and activity-dependent synaptic plasticity. Curr. Opin. Neurobiol. 9, 305–313 ( 1999).

    CAS  Article  Google Scholar 

  27. 27

    Zucker, R. S. Effects of photolabile calcium chelators on fluorescent calcium indicators. Cell Calcium 13, 29–40 (1992).

    CAS  Article  Google Scholar 

  28. 28

    Traynelis, S. F. Software-based correction of single compartment series resistance errors. J. Neurosci. Methods 86, 25– 34 (1998).

    CAS  Article  Google Scholar 

  29. 29

    Xu, T., Naraghi, M., Kang, H. & Neher, E. Kinetic studies of Ca2+ binding and Ca2+ clearance in the cytosol of adrenal chromaffin cells. Biophys. J. 73, 532–545 (1997).

    CAS  Article  Google Scholar 

  30. 30

    Xu-Friedman, M. A. & Regehr, W. G. Presynaptic strontium dynamics and synaptic transmission. Biophys. J. 76, 2029–2042 (1999).

    CAS  Article  Google Scholar 

  31. 31

    Bollmann, J. H., Sakmann, B. & Borst, J. G. G. Calcium sensitivity of glutamate release in a calyx-type terminal. Science (in the press).

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Acknowledgements

We thank T. Sakaba for discussions, and J. Rettig, M. Casado, P. Ascher and R. Fernández-Chacon for critical comments on the manuscript. This work was supported by the Deutsche Forschungsgemeinschaft.

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Correspondence to Ralf Schneggenburger.

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Schneggenburger, R., Neher, E. Intracellular calcium dependence of transmitter release rates at a fast central synapse. Nature 406, 889–893 (2000). https://doi.org/10.1038/35022702

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