Real-Time Chemical Measurements of Dopamine Release in the Brain

Roberts, James G.; Lugo-Morales, Leyda Z.; Loziuk, Philip L.; Sombers, Leslie A.

doi:10.1007/978-1-62703-251-3_16

Cited by 47 publications

(86 citation statements)

References 43 publications

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“…Rats were given a minimum of 2 days habituation to the facility post-transport before surgery was performed. The surgical procedure was performed as described previously, 61 using flat skull stereotaxic coordinates obtained from Paxinos and Watson 1986. Briefly, rats were deeply anesthetized with sodium urethane (1.5 g/kg i.p.)…”

Section: ■ Methodsmentioning

confidence: 99%

Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry

Spanos

Gras-Najjar

Letchworth

et al. 2013

ACS Chem. Neurosci.

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The dopaminergic neurons of the nigrostriatal dopamine (DA) projection from the substantia nigra to the dorsal striatum become dysfunctional and slowly degenerate in Parkinson's disease, a neurodegenerative disorder that afflicts more than one million Americans. There is no specific known cause for idiopathic Parkinson's disease; however, multiple lines of evidence implicate oxidative stress as an underlying factor in both the initiation and progression of the disease. This involves the enhanced generation of reactive oxygen species, including hydrogen peroxide (H 2 O 2 ), whose role in complex biological processes is not well understood. Using fast-scan cyclic voltammetry at bare carbon-fiber microelectrodes, we have simultaneously monitored and quantified H 2 O 2 and DA fluctuations in intact striatal tissue under basal conditions and in response to the initiation of oxidative stress. Furthermore, we have assessed the effect of acute increases in local H 2 O 2 concentration on both electrically evoked DA release and basal DA levels. Increases in endogenous H 2 O 2 in the dorsal striatum attenuated electrically evoked DA release, and also decreased basal DA levels in this brain region. These novel results will help to disambiguate the chemical mechanisms underlying the progression of neurodegenerative disease states, such as Parkinson's disease, that involve oxidative stress.

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Section: ■ Methodsmentioning

confidence: 99%

Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry

Spanos

Gras-Najjar

Letchworth

et al. 2013

ACS Chem. Neurosci.

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“…The current at E p,DA (ordinate) can be plotted versus analyte concentration (abscissa) and the slope of a fitted regression line determines electrode sensitivity (Figure 2D). 1,2 …”

Section: Resultsmentioning

confidence: 99%

“…1 In short, a single carbon fiber was aspirated into a glass capillary, a glass seal was created using a micropipette puller (Narishige, Tokyo, Japan), and the fiber extending past the seal was cut to 100 µm in length. Electrical connection to the carbon-fiber was established via a conductive silver epoxy.…”

Section: Methodsmentioning

confidence: 99%

“…1,2 This approach originated with the work of Millar and colleagues, 3,4 and has seen increasing use in the last decade (Figure 1) due to thorough characterization and technological improvements made largely by Wightman and colleagues. 5–10 When combined with behavioral and pharmacological paradigms, it has provided remarkable information about the molecular mechanisms underlying specific aspects of goal-directed behavior and associative learning, significantly advancing this field.…”

Section: Introductionmentioning

confidence: 99%

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Background Signal as an in Situ Predictor of Dopamine Oxidation Potential: Improving Interpretation of Fast-Scan Cyclic Voltammetry Data

Meunier

Roberts

McCarty

et al. 2017

ACS Chem. Neurosci.

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Background-subtracted fast-scan cyclic voltammetry (FSCV) has emerged as a powerful analytical technique for monitoring sub-second molecular fluctuations in live brain tissue. Despite increasing utilization of FSCV, efforts to improve the accuracy of quantification have been limited due to the complexity of the technique and the dynamic recording environment. It is clear that variable electrode performance renders calibration necessary for accurate quantification; however, the nature of in vivo measurements can make conventional post-calibration difficult, or even impossible. Analyte-specific voltammograms and scaling factors that are critical for quantification can shift or fluctuate in vivo. This is largely due to impedance changes, and the effects of impedance on these measurements have not been characterized. We have previously reported that the background current can be used to predict electrode-specific scaling factors in situ. In this work, we employ model circuits to investigate the impact of impedance on FSCV measurements. Additionally, we take another step toward in situ electrode calibration by using the oxidation potential of quinones on the electrode surface to accurately predict the oxidation potential for dopamine at any point in an electrochemical experiment, as both are dependent on impedance. The model, validated both in adrenal slice and live brain tissue, enables information encoded in the shape of the background voltammogram to determine electrochemical parameters that are critical for accurate quantification. This improves data interpretation and provides a significant next step toward more automated methods for in vivo data analysis.

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“…Thus, carbon-fiber microelectrodes are commonly conditioned immediately prior to data collection 49 . It has also more recently been established, using various spectroscopic techniques including X-ray photoelectron spectroscopy 88 , thermal desorption mass spectrometry 89 , enzyme-immobilized fluorescence microscopy 90, 91 , optical spectroscopy 92 , and Raman spectroscopy 47 , that application of potentials greater than ~1.3V can chemically alter, or even etch, the electrode surface 47, 48, 87 .…”

Section: Resultsmentioning

confidence: 99%

Unmasking the Effects of L-DOPA on Rapid Dopamine Signaling with an Improved Approach for Nafion Coating Carbon-Fiber Microelectrodes

Thomas

White

et al. 2016

Anal. Chem.

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L-DOPA has been the gold standard for symptomatic treatment of Parkinson’s disease. However, its efficacy wanes over time as motor complications develop. Very little is known about how L-DOPA therapy affects the dynamics of fluctuating dopamine concentrations in the striatum on a rapid timescale (seconds). Electrochemical studies investigating the effects of L-DOPA treatment on electrically evoked dopamine release have reported conflicting results with significant variability. We hypothesize that the uncertainty in the electrochemical data is largely due to electrode fouling caused by polymerization of L-DOPA and endogenous catecholamines on the electrode surface. Thus, we have systematically optimized the procedure for fabricating cylindrical, Nafion-coated, carbon-fiber microelectrodes. This has enabled rapid and reliable detection of L-DOPA’s effects on striatal dopamine signaling in intact rat brain using fast-scan cyclic voltammetry. An acute dose of 5 mg/kg L-DOPA had no significant effect on dopamine dynamics, demonstrating the highly efficient regulatory mechanisms at work in the intact brain. In contrast, administration of 200 mg/kg L-DOPA significantly increased the amplitude of evoked dopamine release by ~200%. Overall, this work describes a reliable tool that allows a better measure of L-DOPA augmented dopamine release in vivo, measured using fast-scan cyclic voltammetry. It provides a methodology that improves the stability and performance of the carbon fiber microelectrode when studying the molecular mechanisms underlying L-DOPA therapy, and also promises to benefit a wide variety of studies because Nafion is so commonly used in electroanalytical chemistry.

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Real-Time Chemical Measurements of Dopamine Release in the Brain

Cited by 47 publications

References 43 publications

Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry

Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry

Background Signal as an in Situ Predictor of Dopamine Oxidation Potential: Improving Interpretation of Fast-Scan Cyclic Voltammetry Data

Unmasking the Effects of L-DOPA on Rapid Dopamine Signaling with an Improved Approach for Nafion Coating Carbon-Fiber Microelectrodes

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