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Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal.

Publication ,  Journal Article
Hull, C; Studholme, K; Yazulla, S; von Gersdorff, H
Published in: J Neurophysiol
October 2006

The number and morphology of synaptic ribbons at photoreceptor and bipolar cell terminals has been reported to change on a circadian cycle. Here we sought to determine whether this phenomenon exists at goldfish Mb-type bipolar cell terminals with the aim of exploring the role of ribbons in transmitter release. We examined the physiology and ultrastructure of this terminal around two time points: midday and midnight. Nystatin perforated-patch recordings of membrane capacitance (C(m)) revealed that synaptic vesicle exocytosis evoked by short depolarizations was reduced at night, even though Ca(2+) currents were larger. The efficiency of exocytosis (measured as the DeltaC(m) jump per total Ca(2+) charge influx) was thus significantly lower at night. The paired-pulse ratio remained unchanged, however, suggesting that release probability was not altered. Hence the decreased exocytosis likely reflects a smaller readily releasable vesicle pool at night. Electron microscopy of single sections from intact retinas averaged 65% fewer ribbons at night. Interestingly, the number of active zones did not change from day to night, only the probability of finding a ribbon at an active zone. Additionally, synaptic vesicle halos surrounding the ribbons were more completely filled at night when these on-type bipolar cells are more hyperpolarized. There was no change, however, in the physical dimensions of synaptic ribbons from day to night. These results suggest that the size of the readily releasable vesicle pool and the efficiency of exocytosis are reduced at night when fewer ribbons are present at bipolar cell terminal active zones.

Duke Scholars

Published In

J Neurophysiol

DOI

ISSN

0022-3077

Publication Date

October 2006

Volume

96

Issue

4

Start / End Page

2025 / 2033

Location

United States

Related Subject Headings

  • Synaptic Vesicles
  • Synaptic Membranes
  • Retinal Bipolar Cells
  • Presynaptic Terminals
  • Photoreceptor Cells, Vertebrate
  • Patch-Clamp Techniques
  • Neurology & Neurosurgery
  • Microscopy, Electron
  • Membrane Potentials
  • Goldfish
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Hull, C., Studholme, K., Yazulla, S., & von Gersdorff, H. (2006). Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal. J Neurophysiol, 96(4), 2025–2033. https://doi.org/10.1152/jn.00364.2006
Hull, Court, Keith Studholme, Stephen Yazulla, and Henrique von Gersdorff. “Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal.J Neurophysiol 96, no. 4 (October 2006): 2025–33. https://doi.org/10.1152/jn.00364.2006.
Hull C, Studholme K, Yazulla S, von Gersdorff H. Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal. J Neurophysiol. 2006 Oct;96(4):2025–33.
Hull, Court, et al. “Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal.J Neurophysiol, vol. 96, no. 4, Oct. 2006, pp. 2025–33. Pubmed, doi:10.1152/jn.00364.2006.
Hull C, Studholme K, Yazulla S, von Gersdorff H. Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal. J Neurophysiol. 2006 Oct;96(4):2025–2033.

Published In

J Neurophysiol

DOI

ISSN

0022-3077

Publication Date

October 2006

Volume

96

Issue

4

Start / End Page

2025 / 2033

Location

United States

Related Subject Headings

  • Synaptic Vesicles
  • Synaptic Membranes
  • Retinal Bipolar Cells
  • Presynaptic Terminals
  • Photoreceptor Cells, Vertebrate
  • Patch-Clamp Techniques
  • Neurology & Neurosurgery
  • Microscopy, Electron
  • Membrane Potentials
  • Goldfish