Simultaneous serotonin and dopamine monitoring across timescales by rapid pulse voltammetry with partial least squares regression

Abstract

Many voltammetry methods have been developed to monitor brain extracellular dopamine levels. Fewer approaches have been successful in detecting serotonin in vivo. No voltammetric techniques are currently available to monitor both neurotransmitters simultaneously across timescales, even though they play integrated roles in modulating behavior. We provide proof-of-concept for rapid pulse voltammetry coupled with partial least squares regression (RPV-PLSR), an approach adapted from multi-electrode systems (i.e., electronic tongues) used to identify multiple components in complex environments. We exploited small differences in analyte redox profiles to select pulse steps for RPV waveforms. Using an intentionally designed pulse strategy combined with custom instrumentation and analysis software, we monitored basal and stimulated levels of dopamine and serotonin. In addition to faradaic currents, capacitive currents were important factors in analyte identification arguing against background subtraction. Compared to fast-scan cyclic voltammetry-principal components regression (FSCV-PCR), RPV-PLSR better differentiated and quantified basal and stimulated dopamine and serotonin associated with striatal recording electrode position, optical stimulation frequency, and serotonin reuptake inhibition. The RPV-PLSR approach can be generalized to other electrochemically active neurotransmitters and provides a feedback pipeline for future optimization of multi-analyte, fit-for-purpose waveforms and machine learning approaches to data analysis. Graphical abstract

Optogenetic Stimulation of Midbrain Dopamine Neurons Produces Striatal Serotonin Release

“…Regardless of the mechanism, the present findings indicate that optogenetic stimulation of midbrain dopamine neurons evokes striatal serotonin release. We recently reported similar findings elucidated by rapid-pulse voltammetry . Dopamine–serotonin coupling is likely to be of importance to the facilitation of reward prediction, locomotor control, habit formation, and anhedonia.…”

“…We recently reported similar findings elucidated by rapid-pulse voltammetry. 82 Dopamine− serotonin coupling is likely to be of importance to the ■ METHODS Animal Procedures. Mice were generated at the University of California, Los Angeles (UCLA) from a DAT IREScre line (The Jackson Laboratory, stock no.…”

A Serotonin Story in a Toxicological Model of Parkinsonism: Real Time, In Vivo, Chemical Investigations in Mice

“…We are not able to verify that notion or quantify the change with conventional calibration techniques since the dopamine and serotonin peaks significantly overlap in the potential domain. Over the past few years, there has been an interest to simultaneously measure serotonin and dopamine with voltammetric techniques by using different electrode materials that separate the peaks, (Castagnola et al, 2021;Selvaraju & Ramaraj, 2005;Swamy & Venton, 2007;Zhou et al, 2013;Zhuo et al, 2017) novel waveforms (Movassaghi et al, 2021) and machine learning methods with in vitro mixture datasets. (Bang et al, 2020;Movassaghi et al, 2021) Here we took a novel approach by generating a synthetic, relative dataset from in vivo pharmacologically-validated serotonin and dopamine evoked release signals.…”

“…Over the past few years, there has been an interest to simultaneously measure serotonin and dopamine with voltammetric techniques by using different electrode materials that separate the peaks, (Castagnola et al, 2021;Selvaraju & Ramaraj, 2005;Swamy & Venton, 2007;Zhou et al, 2013;Zhuo et al, 2017) novel waveforms (Movassaghi et al, 2021) and machine learning methods with in vitro mixture datasets. (Bang et al, 2020;Movassaghi et al, 2021) Here we took a novel approach by generating a synthetic, relative dataset from in vivo pharmacologically-validated serotonin and dopamine evoked release signals. We utilized dopamine signals from the striatum, a brain region strongly innervated by dopaminergic neurons, (Cachope & Cheer, 2014) and serotonin signals from the CA2 region of the hippocampus to create a mixture dataset used to train a CNN to predict the relative ratio of serotonin to dopamine in the signal.…”

Multiplexed Monitoring of Neurochemicals via Electrografting-Enabled Site-Selective Functionalization of Aptamers on Field-Effect Transistors

“…Specifically, FSCV possesses better temporal resolution (milliseconds) and sensitivity (nanomolar). Because of that, coupling FSCV or rapid pulse voltammetry with voltammogram analysis (multivariate penalized regression, partial least squares regression, and deep learning) has been used to distinguish voltammograms from multiple neurochemicals, thereby making it possible for multiplexed analysis. ,, FSCV, however, fails to distinguish some structurally similar neurotransmitters, such as dopamine and norepinephrine. − Microdialysis suffers from large temporal resolution (typically several minutes) and low spatial resolution because of the semipermeable membrane and large probe size (150–440 μm in diameter). , Recently, genetically encoded fluorescent sensors have been developed to image the dynamics of neurochemical release in vivo, including DA and glutamate. ,− However, the multiplex monitoring with high selectivity and non-overlapping spectra beyond the dual-color imaging of glutamate and DA is challenging . Additionally, the complicated genetic modification process and the requirements of coupling with fiber photometry for neurochemical monitoring limit the practical applications of these genetically encoded sensors …”