Counting the Number of Glutamate Molecules in Single Synaptic Vesicles
Journal article, 2019

Analytical tools for quantitative measurements of glutamate, the principal excitatory neurotransmitter in the brain, are lacking. Here, we introduce a new enzyme-based amperometric sensor technique for the counting of glutamate molecules stored inside single synaptic vesicles. In this method, an ultra-fast enzyme-based glutamate sensor is placed into a solution of isolated synaptic vesicles, which stochastically rupture at the sensor surface in a potential-dependent manner at a constant negative potential. The continuous amperometric signals are sampled at high speed (10 kHz) to record sub-millisecond spikes, which represent glutamate release from single vesicles that burst open. Glutamate quantification is achieved by a calibration curve that is based on measurements of glutamate release from vesicles pre-filled with various glutamate concentrations. Our measurements show that an isolated single synaptic vesicle encapsulates about 8000 glutamate molecules and is comparable to the measured exocytotic quantal glutamate release in amperometric glutamate sensing in the nucleus accumbens of mouse brain tissue. Hence, this new methodology introduces the means to quantify ultra-small amounts of glutamate and to study synaptic vesicle physiology, pathogenesis, and drug treatments for neuronal disorders where glutamate is involved. ©

Author

Yuanmo Wang

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Hoda Mashadi Fathali

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Analytical Chemistry

Devesh Mishra

Wallenberg Lab.

University of Gothenburg

Thomas Olsson

Chalmers, Physics, Biological Physics

Jacqueline Keighron

New York Institute of Technology

Karolina P. Skibicka

Wallenberg Lab.

University of Gothenburg

Ann-Sofie Cans

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 141 44 17507-17511

Subject Categories

Medical Laboratory and Measurements Technologies

Analytical Chemistry

Medical Equipment Engineering

DOI

10.1021/jacs.9b09414

PubMed

31644274

More information

Latest update

11/22/2019