3D STED Super-Resolution Imaging Strategy for Visualizing Synaptic Nano-architecture in Brain Cryosections

Area of Science:

• Neuroscience
• Cell Biology
• Microscopy

Background:

• Super-resolution imaging of intact brain tissue is limited by light scattering, photobleaching, and probe penetration.
• Visualizing synaptic nano-architecture in postsynaptic densities (PSDs) is challenging due to antigen accessibility issues.

Purpose of the Study:

• To present a protocol for visualizing excitatory synapse nano-architecture in situ using cryosectioning and STED nanoscopy.
• To enable efficient and high-resolution imaging of synaptic structures within their native environment.

Main Methods:

• Utilizing thin (6 μm) brain cryosections for improved probe penetration and consistent resolution.
• Employing tau-stimulated emission depletion (STED) nanoscopy for rapid, high-resolution 3D imaging.
• Optimizing labeling strategies for pre- and postsynaptic nano-architecture using antibodies and nanobodies, considering fixative choice.

Main Results:

• Achieved ~50 nm XY and ~100 nm Z resolution for in situ 3D STED microscopy.
• Demonstrated efficient and even probe penetration throughout cryosections.
• Enabled clear separation of key synaptic features in 3D with minimal photobleaching.

Conclusions:

• This protocol provides robust multiplex imaging of fluorescently labeled synaptic proteins in the brain.
• Offers exceptional spatial resolution for visualizing and quantifying synaptic nanoarchitecture.
• Facilitates the study of molecular synaptic diversity at the nanoscale in situ.