Fast-Scan Cyclic Voltammetry for Ex Vivo Recording of Dopamine Release

Summary

Fast-scan cyclic voltammetry (FCV) measures rapid dopamine dynamics with sub-second resolution using carbon-fibre microelectrodes. This protocol describes FCV in acute mouse brain slices, including electrode fabrication, slice preparation, calibration, and stimulation-based assays to examine how cholinergic interneurons regulate striatal dopamine release under physiological conditions.

Abstract

Fast-Scan Cyclic Voltammetry (FCV) is an electrochemical technique that enables real-time detection of oxidisable neurotransmitters, including dopamine (DA), norepinephrine, and serotonin, with sub-second temporal resolution. By applying a rapidly scanning triangular voltage waveform to a carbon-fibre microelectrode, FCV allows highly sensitive measurement of rapid, transient changes in extracellular neurotransmitter concentrations with excellent temporal precision. This makes FCV particularly well-suited for recording fast neuromodulatory signalling events. This article describes the application of FCV to measure evoked DA release in ex vivo mouse brain slices. The protocol outlines essential steps for carbon-fibre microelectrode fabrication, acute brain slice preparation, electrode conditioning, data acquisition, and post-hoc calibration to convert current signals into absolute DA concentrations. Using the selective β2-containing nicotinic acetylcholine receptor (nAChR) antagonist dihydro-β-erythroidine (DHβE), we demonstrate that nAChR activity has a powerful modulatory influence on striatal DA release. Together, this work highlights FCV as a powerful approach for investigating monoamine transmission across brain regions.

Introduction

Fast-scan cyclic voltammetry (FCV) is an electrochemical technique developed to monitor rapid fluctuations in electroactive neurotransmitters¹. Unlike traditional cyclic voltammetry, which uses slow scan rates¹, FCV applies a triangular potential waveform at a much faster scan rate (typically 400 V/s) through a micrometre-scale carbon-fibre microelectrode, enabling subsecond measurements of neurotransmitter concentration². These high scan rates generate a large but stable background charging current that can be digitally subtracted to isolate the faradaic currents produced by oxidation and reducti....

Protocol

All animal procedures were approved by the University of Exeter Animal Welfare and Ethical Review Board and conducted under Home Office License [PP262252]. The reagents and the equipment used are listed in the Table of Materials.

1. Preparation of carbon-fibre microelectrodes

1. Fill a clean glass container with acetone. Submerge the glass capillaries fully in the acetone, ensuring that each capillary is filled.
2. Using tweezers, insert a single carbon fibre into an acetone-filled capillary. Remove the capillaries from the acetone and allow them to air-dry completely.
3. Load the dri....

Results

DA release amplitudes were quantified from background-subtracted FCV recordings. For each trial, the background signal was generated by averaging five stable pre-stimulation voltammograms, enabling clear isolation of the oxidation peak. DA release was measured as the peak oxidation current at approximately +0.6 V. At the end of each experiment, electrodes were calibrated, and peak oxidation currents were converted to DA concentrations using the electrode-specific sensitivity factor (nA/µM). To facilitate comparisons acro.......

Discussion

This protocol describes the fundamental procedures for measuring evoked DA release using FCV in acute mouse brain slices and provides a comprehensive guide to the essential workflow. In addition to DA-specific applications, FCV can also be used to detect other neurotransmitters, such as noradrenaline and serotonin, in both ex vivo and in vivo preparations^21,22,23. Here, we highlight the key components of the me.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acetone	Sigma-Aldrich	534064-500ml
Calcium Chloride	Sigma-Aldrich	21115-100ml	1M solution
Carbon Fiber	Goodfellow Cambridge Limited	LS596012 APB
Concentric Bipolar Electrode	FHC	300197	Stimulus Electrode
Dihydro-β-erythroidine hydrobromide	Tocris Biosciences	12A/295293
Dopamine HCl	apexbt	B1482
Fast Scan Cyclic Voltammetry Potentiostat System	WaveNeuro	AF01FSCV1
Glass Capillaries	Harvard apparatus	GC200F-10
Glucose	Sigma-Aldrich	SLCQ7550
Halogen Power Supply	Olympus	TH4
Isolated Current Stimulator	Digitimer	DS3
Magnesium chloride hexahyrate	Sigma-Aldrich	M2670
Multicore Cable	Multicomp Pro	3372784
Perchloric acid	Fisher science	UN2920	0.1M in glacial acetic acid
Peristaltic Pumps	Gilson	MINIPLUS 3
Potassium chloride	Sigma-Aldrich	P9541
Prime BSI Express	Teledyne	01-PRIME-BSI-EXP
Silver Conductive Paint	RS Components	RS 186-3600
Silver/Silver Chloride Reference	World Precision Instruments	0226E	Reference Electrode
SliceScope	Scientifica	Pro 2000
Sodium bicarbonate	Sigma-Aldrich	S5761
Sodium chloride	Fisher science	2402665
Sodium phosphate monobasic	Sigma-Aldrich	S5011
Stimulus Generator	Multichannel systems	STG5
Sucrose	Millipore	84100
Vertical microelectrode puller	Narishige	PC-100