Structural Heterogeneity of the GABAergic Tripartite Synapse
Cindy Brunskine1, Stefan Passlick1, Christian Henneberger1,2
1Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
Cells
|October 14, 2022
Summary
Astrocytes interact differently with GABAergic and glutamatergic synapses. Astrocytic processes are more abundant at GABAergic synapses with larger gephyrin clusters, but less abundant overall near GABAergic synapses compared to glutamatergic ones.
Area of Science:
- Neuroscience
- Cell Biology
- Synaptic Plasticity
Background:
- The tripartite synapse involves pre- and postsynaptic neurons and surrounding astrocytes.
- Astrocytic process organization varies significantly at glutamatergic synapses.
- The organization of astrocytic processes at GABAergic synapses is less understood, despite known bidirectional signaling.
Purpose of the Study:
- To investigate the structural organization of astrocytic processes at GABAergic synapses.
- To compare astrocytic coverage at GABAergic versus glutamatergic synapses in the hippocampus.
- To understand the functional implications of astrocytic arrangement at inhibitory synapses.
Main Methods:
- Super-resolution expansion microscopy was used to visualize GABAergic synapses.
- Presynaptic vesicular GABA transporter and postsynaptic gephyrin were key markers.
- Astrocytic process volume near synapses was quantified and compared.
Main Results:
- Astrocytic processes were more abundant at GABAergic synapses with larger postsynaptic gephyrin clusters.
- Astrocytic processes were less abundant around GABAergic synapses compared to glutamatergic synapses.
- Subsynaptic heterogeneity in GABAergic synapse structure was documented.
Conclusions:
- Astrocytes exhibit differential spatial arrangements around GABAergic and glutamatergic synapses.
- The observed arrangement suggests selective astrocyte-synapse interactions.
- This specific arrangement may enhance GABA reuptake efficiency into presynaptic terminals.
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