Tissue multicolor STED nanoscopy of presynaptic proteins in the calyx of Held

PLoS One. 2013 Apr 26;8(4):e62893. doi: 10.1371/journal.pone.0062893. Print 2013.

Abstract

The calyx of Held, a large glutamatergic terminal in the mammalian auditory brainstem has been extensively employed to study presynaptic structure and function in the central nervous system. Nevertheless, the nanoarchitecture of presynaptic proteins and subcellular components in the calyx terminal and its relation to functional properties of synaptic transmission is only poorly understood. Here, we use stimulated emission depletion (STED) nanoscopy of calyces in thin sections of aldehyde-fixed rat brain tissue to visualize immuno-labeled synaptic proteins including VGluT1, synaptophysin, Rab3A and synapsin with a lateral resolution of approximately 40 nm. Excitation multiplexing of suitable fluorescent dyes deciphered the spatial arrangement of the presynaptic phospho-protein synapsin relative to synaptic vesicles labeled with anti-VGluT1. Both predominantly occupied the same focal volume, yet may exist in exclusive domains containing either VGluT1 or synapsin immunoreactivity. While the latter have been observed with diffraction-limited fluorescence microscopy, STED microscopy for the first time revealed VGluT1-positive domains lacking synapsins. This observation supports the hypothesis that molecularly and structurally distinct synaptic vesicle pools operate in presynaptic nerve terminals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Auditory Cortex / metabolism
  • Auditory Cortex / ultrastructure*
  • Fixatives
  • Fluorescent Dyes
  • Gene Expression
  • Microscopy, Fluorescence / methods
  • Microtomy
  • Phosphorylation
  • Presynaptic Terminals / metabolism
  • Presynaptic Terminals / ultrastructure*
  • Rats
  • Rats, Sprague-Dawley
  • Synapsins / genetics
  • Synapsins / metabolism
  • Synaptic Transmission / physiology*
  • Synaptic Vesicles / metabolism
  • Synaptic Vesicles / ultrastructure*
  • Synaptophysin / genetics
  • Synaptophysin / metabolism
  • Vesicular Glutamate Transport Protein 1 / genetics
  • Vesicular Glutamate Transport Protein 1 / metabolism
  • rab3A GTP-Binding Protein / genetics
  • rab3A GTP-Binding Protein / metabolism

Substances

  • Fixatives
  • Fluorescent Dyes
  • Slc17a7 protein, rat
  • Synapsins
  • Synaptophysin
  • Syp protein, rat
  • Vesicular Glutamate Transport Protein 1
  • rab3A GTP-Binding Protein

Grants and funding

This work has been partially supported by the CellNetworks Cluster of Excellence (EXC81, T.K.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study.