Optical Measurement of Glutamate Release at a Fast Central Synapse

by Paul Jakob Habakuk Hain
Doctoral thesis
Date of Examination:2024-07-23
Date of issue:2025-04-02
Advisor:Prof. Dr. Tobias Moser
Referee:Prof. Dr. Tobias Moser
Referee:Prof. Dr. Erwin Neher
Referee:Prof. Dr. Ralf Dressel
Persistent Address: http://dx.doi.org/10.53846/goediss-10632

 

 

Files in this item

Name:main.pdf
Size:1.83Mb
Format:PDF
Description:Dissertation

The following license files are associated with this item:

Abstract

English

Recent advances in the development optogenetic indicators have enabled optical measurements of neurotransmitter release and dynamics in the synaptic cleft. The precise information about spatial and temporal neurotransmitter dynamics can be used to gain insight into presynaptic function, which is independent of established electrophysiological techniques. This study utilizes the genetically- encoded glutamate indicator iGluSnFR to monitor glutamate dynamics at the endbulb of Held synapse. Here, iGluSnFR is expressed in mouse spiral ganglion neuron with a viral vector approach to compare electrophysiological and optical readouts of presynaptic function and short-term synaptic plasticity. Immunohistochemical stainings show that iGluSnFR is robustly expressed in the cochlear nucleus and spiral ganglion following intracochlear injection of a viral vector. In response to different stimulation paradigms, iGluSnFR shows a clear and graduated fluorescent signal. In order to probe putative effects of iGluSnFR expression on physiological neurotransmission, electrophysiological measurements of injected and control animals are compared, which show that iGluSnFR expression slightly alters the time course of spontaneous postsynaptic currents, but is unlikely to impact measurements of evoked synchronous release of many synaptic vesicles. Quantitative comparison of iGluSnFR responses to electrophyiological measurements show that iGluSnFR robustly and approximately linearly reports glutamate release during synaptic transmission at the endbulb of Held and allows assessment of short-term plasticity during high-frequency train stimuli.
Keywords: patch-clamp electrophysiology; AAV-mediated gene transfer; glutamate imaging; synaptic plasticity; endbulb of Held
Schlagwörter: glutamate imaging; synaptic plasticity; endbulb of Held; patch-clamp electrophysiology; AAV-mediated gene transfer
 
Statistik