101
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Takmakov P, Zachek MK, Keithley RB, Walsh PL, Donley C, McCarty GS, Wightman RM. Carbon microelectrodes with a renewable surface. Anal Chem 2010; 82:2020-8. [PMID: 20146453 DOI: 10.1021/ac902753x] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electrode fouling decreases sensitivity and can be a substantial limitation in electrochemical experiments. In this work we describe an electrochemical procedure that constantly renews the surface of a carbon microelectrode using periodic triangle voltage excursions to an extended anodic potential at a scan rate of 400 V s(-1). This methodology allows for the regeneration of an electrochemically active surface and restores electrode sensitivity degraded by irreversible adsorption of chemical species. We show that repeated voltammetric sweeps to moderate potentials in aqueous solution causes oxidative etching of carbon thereby constantly renewing the electrochemically active surface. Oxidative etching was established by tracking surface-localized fluorine atoms with XPS, by monitoring changes in carbon surface morphology with AFM on pyrolyzed photoresist films, and also by optical and electron microscopy. The use of waveforms with extended anodic potentials showed substantial increases in sensitivity toward the detection of catechols. This enhancement arose from the adsorption of the catechol moiety that could be maintained with a constant regeneration of the electrode surface. We also demonstrate that application of the extended waveform could restore the sensitivity of carbon microelectrodes diminished by irreversible adsorption (electrode fouling) of byproducts resulting from the electrooxidation and polymerization of tyramine. Overall, this work brings new insight into the factors that affect electrochemical processes at carbon electrodes and provides a simple method to remove or reduce fouling problems associated with many electrochemical experiments.
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Affiliation(s)
- Pavel Takmakov
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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102
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Roberts JG, Moody BP, McCarty GS, Sombers LA. Specific oxygen-containing functional groups on the carbon surface underlie an enhanced sensitivity to dopamine at electrochemically pretreated carbon fiber microelectrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9116-22. [PMID: 20166750 DOI: 10.1021/la9048924] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The in vivo use of carbon-fiber microelectrodes for neurochemical investigation has proven to be selective and sensitive when coupled with background-subtracted fast-scan cyclic voltammetry (FSCV). Various electrochemical pretreatments have been established to enhance the sensitivity of these sensors; however, the fundamental chemical mechanisms underlying these enhancement strategies remain poorly understood. We have investigated an electrochemical pretreatment in which an extended triangular waveform from -0.5 to 1.8 V is applied to the electrode prior to the voltammetric detection of dopamine using a more standard waveform ranging from -0.4 to 1.3 V. This pretreatment enhances the electron-transfer kinetics and significantly improves sensitivity. To gain insight into the chemical mechanism, the electrodes were studied using common analytical techniques. Contact atomic force microscopy (AFM) was used to demonstrate that the surface roughness was not altered on the nanoscale by electrochemical pretreatment. Raman spectroscopy was utilized to investigate oxide functionalities on the carbon surface and confirmed that carbonyl and hydroxyl functional groups were increased by electrochemical conditioning. Spectra collected after the selective chemical modification of these groups implicate the hydroxyl functionality, rather than the carbonyl, as the major contributor to the enhanced electrochemical signal. Finally, we have demonstrated that this electrochemical pretreatment can be used to create carbon microdisc electrodes with sensitivities comparable to those associated with larger, conventionally treated cylindrical carbon fiber microelectrodes.
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Affiliation(s)
- James G Roberts
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA
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103
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In vivo voltammetric monitoring of catecholamine release in subterritories of the nucleus accumbens shell. Neuroscience 2010; 169:132-42. [PMID: 20451589 DOI: 10.1016/j.neuroscience.2010.04.076] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/29/2010] [Accepted: 04/30/2010] [Indexed: 11/23/2022]
Abstract
Fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes has been used to demonstrate that sub-second changes in catecholamine concentration occur within the nucleus accumbens (NAc) shell during motivated behaviors, and these fluctuations have been attributed to rapid dopamine signaling. However, FSCV cannot distinguish between dopamine and norepinephrine, and caudal regions of the NAc shell receive noradrenergic projections. Therefore, in the present study, we examined the degree to which norepinephrine contributes to catecholamine release within rostral and caudal portion of NAc shell. Analysis of tissue content revealed that dopamine was the major catecholamine detectable in the rostral NAc shell, whereas both dopamine and norepinephrine were found in the caudal subregion. To examine releasable catecholamines, electrical stimulation was used to evoke release in anesthetized rats with either stimulation of the medial forebrain bundle, a pathway containing both dopaminergic and noradrenergic projections to the NAc, or the ventral tegmental area/substantia nigra, the origin of dopaminergic projections. The catecholamines were distinguished by their responses to different pharmacological agents. The dopamine autoreceptor blocker, raclopride, as well as the monoamine and dopamine transporter blockers, cocaine and GBR 12909, increased evoked catecholamine overflow in both the rostral and caudal NAc shell. The norepinephrine autoreceptor blocker, yohimbine, and the norepinephrine transporter blocker, desipramine, increased catecholamine overflow in the caudal NAc shell without significant alteration of evoked responses in the rostral NAc shell. Thus, the neurochemical and pharmacological results show that norepinephrine signaling is restricted to caudal portions of the NAc shell. Following raclopride and cocaine or raclopride and GBR 12909, robust catecholamine transients were observed within the rostral shell but these were far less apparent in the caudal NAc shell, and they did not occur following yohimbine and desipramine. Taken together, the data demonstrate that catecholamine signals in the rostral NAc shell detected by FSCV are due to change in dopamine transmission.
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104
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McCarty GS, Moody B, Zachek MK. Enhancing Electrochemical Detection by Scaling Solid State Nanogaps. J Electroanal Chem (Lausanne) 2010; 643:9-14. [PMID: 20454636 PMCID: PMC2863020 DOI: 10.1016/j.jelechem.2010.03.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability to quickly and inexpensively fabricate planar solid state nanogaps has enabled research to be effectively performed on devices down to just a few nanometers. Here, nanofabricated electrode pairs with electrode-to-electrode spacings of <4, 6 and 20 nm are utilized for monitoring an electroactive molecules, dopamine, in ionic solution. The results show a several order of magnitude enhancement of the electrochemical signal, collected current, for the solid state nanogaps with 6 nm electrode-electrode spacings as compared to traditional microelectrodes. The data from the <4 nm and 20 nm solid state nanogaps verify that this enhancement is due to cycling of the redox molecules in the confined geometry of the nanogap. In addition the data collected for the <4 nm nanogap emphasizes and reinforces that scaling does have limits and that as device sizes move to the few nanometer scale, the influence of a molecule's size and other physical properties becomes increasingly important and can eventually dominate the generated signals.
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Affiliation(s)
- Gregory S. McCarty
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh NC 27695
| | - Benjamin Moody
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh NC 27695
| | - Matthew K. Zachek
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh NC 27695
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105
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Roham M, Blaha CD, Garris PA, Lee KH, Mohseni P. A configurable IC for wireless real-time in vivo monitoring of chemical and electrical neural activity. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:4222-5. [PMID: 19963812 DOI: 10.1109/iembs.2009.5333089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A 16-channel chip for wireless in vivo recording of chemical and electrical neural activity is described. The 7.83-mm2 IC is fabricated using a 0.5-microm CMOS process and incorporates a 71-microW, 3rd-order, configurable, DeltaSigma modulator per channel, achieving an input-referred noise of 4.69 microVrms in 4-kHz BW and 94.1 pArms in 5-kHz BW for electrical and fastscan voltammetric chemical neurosensing, respectively. Brain extracellular levels of dopamine elicited by electrical stimulation of the medial forebrain bundle have been recorded wirelessly on multiple channels using 300-V/s fast-scan cyclic voltammetry in the anesthetized rat.
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Affiliation(s)
- Masoud Roham
- Electrical Engineering and Computer Science Department, Case Western Reserve University, Cleveland, OH, USA
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106
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Shon YM, Chang SY, Tye SJ, Kimble CJ, Bennet KE, Blaha CD, Lee KH. Comonitoring of adenosine and dopamine using the Wireless Instantaneous Neurotransmitter Concentration System: proof of principle. J Neurosurg 2010; 112:539-48. [PMID: 19731995 DOI: 10.3171/2009.7.jns09787] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The authors of previous studies have demonstrated that local adenosine efflux may contribute to the therapeutic mechanism of action of thalamic deep brain stimulation (DBS) for essential tremor. Real-time monitoring of the neurochemical output of DBS-targeted regions may thus advance functional neurosurgical procedures by identifying candidate neurotransmitters and neuromodulators involved in the physiological effects of DBS. This would in turn permit the development of a method of chemically guided placement of DBS electrodes in vivo. Designed in compliance with FDA-recognized standards for medical electrical device safety, the authors report on the utility of the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for real-time comonitoring of electrical stimulation-evoked adenosine and dopamine efflux in vivo, utilizing fast-scan cyclic voltammetry (FSCV) at a polyacrylonitrile-based (T-650) carbon fiber microelectrode (CFM). METHODS The WINCS was used for FSCV, which consisted of a triangle wave scanned between -0.4 and +1.5 V at a rate of 400 V/second and applied at 10 Hz. All voltages applied to the CFM were with respect to an Ag/AgCl reference electrode. The CFM was constructed by aspirating a single T-650 carbon fiber (r = 2.5 microm) into a glass capillary and pulling to a microscopic tip using a pipette puller. The exposed carbon fiber (the sensing region) extended beyond the glass insulation by approximately 50 microm. Proof of principle tests included in vitro measurements of adenosine and dopamine, as well as in vivo measurements in urethane-anesthetized rats by monitoring adenosine and dopamine efflux in the dorsomedial caudate putamen evoked by high-frequency electrical stimulation of the ventral tegmental area and substantia nigra. RESULTS The WINCS provided reliable, high-fidelity measurements of adenosine efflux. Peak oxidative currents appeared at +1.5 V and at +1.0 V for adenosine, separate from the peak oxidative current at +0.6 V for dopamine. The WINCS detected subsecond adenosine and dopamine efflux in the caudate putamen at an implanted CFM during high-frequency stimulation of the ventral tegmental area and substantia nigra. Both in vitro and in vivo testing demonstrated that WINCS can detect adenosine in the presence of other easily oxidizable neurochemicals such as dopamine comparable to the detection abilities of a conventional hardwired electrochemical system for FSCV. CONCLUSIONS Altogether, these results demonstrate that WINCS is well suited for wireless monitoring of high-frequency stimulation-evoked changes in brain extracellular concentrations of adenosine. Clinical applications of selective adenosine measurements may prove important to the future development of DBS technology.
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Affiliation(s)
- Young-Min Shon
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA
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107
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Petrovic J, Walsh PL, Thornley KT, Miller CE, Wightman RM. Real-time monitoring of chemical transmission in slices of the murine adrenal gland. Endocrinology 2010; 151:1773-83. [PMID: 20181796 PMCID: PMC2850225 DOI: 10.1210/en.2009-1324] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The real-time electrochemical detection of catecholamine secretion from murine adrenal slices using fast-scan cyclic voltammetry (FSCV) and amperometry at carbon fiber microelectrodes is described. Bright-field and immunofluorescent microscopy supported that chromaffin cells in the adrenal medulla are organized into clusters and positively stain for tyrosine hydroxylase confirming that they are catecholaminergic. Spontaneous exocytotic catecholamine events were observed inside chromaffin cell clusters with both FSCV and amperometry and were modulated by the nicotinic acetylcholine receptor antagonist hexamethonium and low extracellular calcium. Reintroduction of extracellular calcium and pressure ejection of acetylcholine caused the frequency of spikes to increase back to predrug levels. Electrical stimulation caused the synchronous secretion from multiple cells within the gland, which were modulated by nicotinic acetylcholine receptors but not muscarinic receptors or gap junctions. Furthermore, electrically stimulated release was abolished with perfusion of low extracellular calcium or tetrodotoxin, indicating that the release requires electrical excitability. An extended waveform was used to study the spontaneous and stimulated release events to determine their chemical content by FSCV. Consistent with total content analysis and immunohistochemical studies, about two thirds of the cells studied spontaneously secreted epinephrine, whereas one third secreted norepinephrine. Whereas adrenergic sites contained mostly epinephrine during electrical stimulation, noradrenergic sites contained a mixture of the catecholamines showing the heterogeneity of the adrenal medulla.
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Affiliation(s)
- Jelena Petrovic
- Neuroscience Center (R.M.W.), Caudill Laboratories, Venable Hall B-5, CB 3290, Chapel Hill, North Carolina 27599-3290, USA
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108
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109
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High frequency stimulation of the subthalamic nucleus evokes striatal dopamine release in a large animal model of human DBS neurosurgery. Neurosci Lett 2010; 475:136-40. [PMID: 20347936 DOI: 10.1016/j.neulet.2010.03.060] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2009] [Revised: 02/08/2010] [Accepted: 03/21/2010] [Indexed: 11/21/2022]
Abstract
Subthalamic nucleus deep brain stimulation (STN DBS) ameliorates motor symptoms of Parkinson's disease, but the precise mechanism is still unknown. Here, using a large animal (pig) model of human STN DBS neurosurgery, we utilized fast-scan cyclic voltammetry in combination with a carbon-fiber microelectrode (CFM) implanted into the striatum to monitor dopamine release evoked by electrical stimulation at a human DBS electrode (Medtronic 3389) that was stereotactically implanted into the STN using MRI and electrophysiological guidance. STN electrical stimulation elicited a stimulus time-locked increase in striatal dopamine release that was both stimulus intensity- and frequency-dependent. Intensity-dependent (1-7V) increases in evoked dopamine release exhibited a sigmoidal pattern attaining a plateau between 5 and 7V of stimulation, while frequency-dependent dopamine release exhibited a linear increase from 60 to 120Hz and attained a plateau thereafter (120-240Hz). Unlike previous rodent models of STN DBS, optimal dopamine release in the striatum of the pig was obtained with stimulation frequencies that fell well within the therapeutically effective frequency range of human DBS (120-180Hz). These results highlight the critical importance of utilizing a large animal model that more closely represents implanted DBS electrode configurations and human neuroanatomy to study neurotransmission evoked by STN DBS. Taken together, these results support a dopamine neuronal activation hypothesis suggesting that STN DBS evokes striatal dopamine release by stimulation of nigrostriatal dopaminergic neurons.
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110
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Annangudi SP, Luszpak AE, Kim SH, Ren S, Hatcher NG, Weiler IJ, Thornley KT, Kile BM, Wightman RM, Greenough WT, Sweedler JV. Neuropeptide Release is Impaired in a Mouse Model of Fragile X Mental Retardation Syndrome. ACS Chem Neurosci 2010; 1:306-314. [PMID: 20495672 PMCID: PMC2873207 DOI: 10.1021/cn900036x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 12/17/2009] [Indexed: 02/05/2023] Open
Abstract
Fragile X syndrome (FXS), an inherited disorder characterized by mental retardation and autismlike behaviors, is caused by the failure to transcribe the gene for fragile X mental retardation protein (FMRP), a translational regulator and transporter of select mRNAs. FXS model mice (Fmr1 KO mice) exhibit impaired neuropeptide release. Release of biogenic amines does not differ between wild-type (WT) and Fmr1 KO mice. Rab3A, an mRNA cargo of FMRP involved in the recruitment of vesicles, is decreased by ∼50% in synaptoneurosomes of Fmr1 KO mice; however, the number of dense-core vesicles (DCVs) does not differ between WT and Fmr1 KO mice. Therefore, deficits associated with FXS may reflect this aberrant vesicle release, specifically involving docking and fusion of peptidergic DCVs, and may lead to defective maturation/maintenance of synaptic connections.
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Affiliation(s)
| | | | | | | | | | | | - Keith T. Thornley
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Brian M. Kile
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - R. Mark Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - William T. Greenough
- Beckman Institute
- Neuroscience Program
- Departments of Psychology, Psychiatry, and Cell and Structural Biology
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111
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Fabrication of a PANI/Au nanocomposite modified nanoelectrode for sensitive dopamine nanosensor design. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2009.08.048] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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112
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Park J, Kile BM, Wightman RM. In vivo voltammetric monitoring of norepinephrine release in the rat ventral bed nucleus of the stria terminalis and anteroventral thalamic nucleus. Eur J Neurosci 2009; 30:2121-33. [PMID: 20128849 DOI: 10.1111/j.1460-9568.2009.07005.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The role and contribution of the dense noradrenergic innervation in the ventral bed nucleus of the stria terminalis (vBNST) and anteroventral thalamic nucleus (AV) to biological function and animal behaviors is poorly understood due to the small size of these nuclei. The aim of this study was to compare norepinephrine release and uptake in the vBNST with that in the AV of anesthetized rats. Measurements were made in vivo with fast-scan cyclic voltammetry following electrical stimulation of noradrenergic projection pathways, either the dorsal noradrenergic bundle (DNB) or the ventral noradrenergic bundle (VNB). The substance detected was identified as norepinephrine based upon voltammetric, anatomical, neurochemical and pharmacological evidence. Fast-scan cyclic voltammetry enables the selective monitoring of local norepinephrine overflow in the vBNST evoked by the stimulation of either the DNB or the VNB while norepinephrine in the AV was only evoked by DNB stimulation. The alpha2-adrenoceptor antagonist yohimbine and the norepinephrine uptake inhibitor desipramine increased norepinephrine overflow and slowed its disappearance in both regions. However, control of extracellular norepinephrine by both autoreceptors and uptake was greater in the AV. The greater control exerted by autoreceptors and uptake in the AV resulted in reduced extracellular concentration compared with the v BNST when large numbers of stimulation pulses were employed. The differences in noradrenergic transmission observed in the terminal fields of the v BNST and the AV may differentially regulate activity in these two regions that both contain high densities of norepinephrine terminals.
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Affiliation(s)
- Jinwoo Park
- Department of Chemistry and Neuroscience Center, University of North Carolina , Chapel Hill, NC 27599-3290, USA
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113
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Kita JM, Kile BM, Parker LE, Wightman RM. In vivo measurement of somatodendritic release of dopamine in the ventral tegmental area. Synapse 2009; 63:951-60. [PMID: 19593821 DOI: 10.1002/syn.20676] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ventral tegmental area (VTA), the locus of mesolimbic dopamine cell bodies, contains dopamine. Experiments in brain slices have demonstrated that VTA dopamine can be released by local electrical stimulation. Measurements with both push-pull cannula and microdialysis in intact animals have also obtained evidence for releasable dopamine. Here we demonstrate that dopamine release in the VTA can be evoked by remote stimulations of the medial forebrain bundle (MFB) in the anesthetized rat. In initial experiments, the MFB was electrically stimulated while a carbon-fiber electrode was lowered to the VTA, with recording by fast-scan cyclic voltammetry. While release was not observed with the carbon fiber 4-6 mm below dura, a voltammetric response was observed at 6-8 mm below dura, but the voltammogram was poorly defined. At lower depths, in the VTA, dopamine release was evoked. Immunohistochemistry experiments with antibodies for tyrosine hydroxylase (TH) confirmed that dopamine processes were primarily found below 8 mm. Similarly, tissue content determined by liquid chromatography revealed serotonin but not dopamine dorsal to 8 mm with both dopamine and serotonin at lower depths. Evaluation of the VTA signal by pharmacological means showed that it increased with inhibitors of dopamine uptake, but release was not altered by D2 agents. Dopamine release in the VTA was frequency dependent and could be exhausted by stimulations longer than 5 s. Thus, VTA dopamine release can be evoked in vivo by remote stimulations and it resembles release in terminal regions, possessing a similar uptake mechanism and a finite releasable storage pool.
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Affiliation(s)
- Justin M Kita
- Department of Chemistry and Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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114
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Hashemi P, Dankoski EC, Petrovic J, Keithley RB, Wightman RM. Voltammetric detection of 5-hydroxytryptamine release in the rat brain. Anal Chem 2009; 81:9462-71. [PMID: 19827792 PMCID: PMC2783829 DOI: 10.1021/ac9018846] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
5-Hydroxytryptamine (5-HT) is an important molecule in the brain that is implicated in mood and emotional processes. In vivo, its dynamic release and uptake kinetics are poorly understood due to a lack of analytical techniques for its rapid measurement. Whereas fast-scan cyclic voltammetry with carbon fiber microelectrodes is used frequently to monitor subsecond dopamine release in freely moving and anesthetized rats, the electrooxidation of 5-HT forms products that quickly polymerize and irreversibly coat the carbon electrode surface. Previously described modifications of the electrochemical waveform allow stable and sensitive 5-HT measurements in mammalian tissue slice preparations and in the brain of fruit fly larvae. For in vivo applications in mammals, however, the problem of electrode deterioration persists. We identify the root of this problem to be fouling by extracellular metabolites such as 5-hydoxyindole acetic acid (5-HIAA), which is present in 200-1000 times the concentration of 5-HT and displays similar electrochemical properties, including filming of the electrode surface. To impede access of the 5-HIAA to the electrode surface, a thin layer of Nafion, a cation exchange polymer, has been electrodeposited onto cylindrical carbon-fiber microelectrodes. The presence of the Nafion film was confirmed with environmental scanning electron microscopy and was demonstrated by the diminution of the voltammetric signals for 5-HIAA as well as other common anionic species. The modified microelectrodes also display increased sensitivity to 5-HT, yielding a characteristic cyclic voltammogram that is easily distinguishable from other common electroactive brain species. The thickness of the Nafion coating and a diffusion coefficient (D) in the film for 5-HT were evaluated by measuring permeation through Nafion. In vivo, we used physiological, anatomical, and pharmacological evidence to validate the signal as 5-HT. Using Nafion-modified microelectrodes, we present the first endogenous recording of 5-HT in the mammalian brain.
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Affiliation(s)
- Parastoo Hashemi
- Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
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115
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Abstract
Exocytosis, the fusion of intracellular vesicles with the membrane and subsequent release of vesicular contents, is important in intercellular communication. The release event is a rapid process (milliseconds), hence detection of released chemicals requires a detection scheme that is both sensitive and has rapid temporal dynamics. Electrochemistry at carbon-fiber microelectrodes allows time-resolved exocytosis of electroactive catecholamines to be observed at very low levels. When coupled with constant-potential amperometry, the number of molecules released and the kinetics of quantal release can be determined. The rapid response time (milliseconds) of microelectrodes makes them well suited for monitoring the dynamic process of exocytosis.
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116
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Bledsoe JM, Kimble CJ, Covey DP, Blaha CD, Agnesi F, Mohseni P, Whitlock S, Johnson DM, Horne A, Bennet KE, Lee KH, Garris PA. Development of the Wireless Instantaneous Neurotransmitter Concentration System for intraoperative neurochemical monitoring using fast-scan cyclic voltammetry. J Neurosurg 2009; 111:712-23. [PMID: 19425890 PMCID: PMC2808191 DOI: 10.3171/2009.3.jns081348] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Emerging evidence supports the hypothesis that modulation of specific central neuronal systems contributes to the clinical efficacy of deep brain stimulation (DBS) and motor cortex stimulation (MCS). Real-time monitoring of the neurochemical output of targeted regions may therefore advance functional neurosurgery by, among other goals, providing a strategy for investigation of mechanisms, identification of new candidate neurotransmitters, and chemically guided placement of the stimulating electrode. The authors report the development of a device called the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for intraoperative neurochemical monitoring during functional neurosurgery. This device supports fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for real-time, spatially and chemically resolved neurotransmitter measurements in the brain. METHODS The FSCV study consisted of a triangle wave scanned between -0.4 and 1 V at a rate of 300 V/second and applied at 10 Hz. All voltages were compared with an Ag/AgCl reference electrode. The CFM was constructed by aspirating a single carbon fiber (r = 2.5 mum) into a glass capillary and pulling the capillary to a microscopic tip by using a pipette puller. The exposed carbon fiber (that is, the sensing region) extended beyond the glass insulation by approximately 100 microm. The neurotransmitter dopamine was selected as the analyte for most trials. Proof-of-principle tests included in vitro flow injection and noise analysis, and in vivo measurements in urethane-anesthetized rats by monitoring dopamine release in the striatum following high-frequency electrical stimulation of the medial forebrain bundle. Direct comparisons were made to a conventional hardwired system. RESULTS The WINCS, designed in compliance with FDA-recognized consensus standards for medical electrical device safety, consisted of 4 modules: 1) front-end analog circuit for FSCV (that is, current-to-voltage transducer); 2) Bluetooth transceiver; 3) microprocessor; and 4) direct-current battery. A Windows-XP laptop computer running custom software and equipped with a Universal Serial Bus-connected Bluetooth transceiver served as the base station. Computer software directed wireless data acquisition at 100 kilosamples/second and remote control of FSCV operation and adjustable waveform parameters. The WINCS provided reliable, high-fidelity measurements of dopamine and other neurochemicals such as serotonin, norepinephrine, and ascorbic acid by using FSCV at CFM and by flow injection analysis. In rats, the WINCS detected subsecond striatal dopamine release at the implanted sensor during high-frequency stimulation of ascending dopaminergic fibers. Overall, in vitro and in vivo testing demonstrated comparable signals to a conventional hardwired electrochemical system for FSCV. Importantly, the WINCS reduced susceptibility to electromagnetic noise typically found in an operating room setting. CONCLUSIONS Taken together, these results demonstrate that the WINCS is well suited for intraoperative neurochemical monitoring. It is anticipated that neurotransmitter measurements at an implanted chemical sensor will prove useful for advancing functional neurosurgery.
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Affiliation(s)
| | | | - Daniel P. Covey
- Department of Biological Sciences, Illinois State University, Normal, Illinois
| | | | - Filippo Agnesi
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Pedram Mohseni
- Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio
| | | | | | - April Horne
- Division of Engineering, Mayo Clinic, Rochester, Minnesota
| | | | - Kendall H. Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Paul A. Garris
- Department of Biological Sciences, Illinois State University, Normal, Illinois
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117
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Owesson-White CA, Ariansen J, Stuber GD, Cleaveland NA, Cheer JF, Wightman RM, Carelli RM. Neural encoding of cocaine-seeking behavior is coincident with phasic dopamine release in the accumbens core and shell. Eur J Neurosci 2009; 30:1117-27. [PMID: 19735286 DOI: 10.1111/j.1460-9568.2009.06916.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mesolimbic dopamine neurons projecting from the ventral tegmental area to the nucleus accumbens (NAc) are part of a complex circuit mediating cocaine-directed behaviors. However, the precise role of rapid (subsecond) dopamine release within the primary subregions of the NAc (the core and shell) and its relationship to NAc cell firing during this behavior remain unknown. Here, using fast-scan cyclic voltammetry in rats we report rapid dopamine signaling in both the core and shell; however, significant differences were observed in the timing of dopamine release events within seconds of the cocaine-reinforced response during self-administration sessions. Importantly, simultaneous voltammetric and electrophysiological recordings from the same electrode reveal that, at certain sites within both subregions, neurons exhibiting patterned activation were observed at locations where rapid dopamine release was present; the greater the strength of the neural signal the larger the dopamine release event. In addition, it was at those locations that electrically-evoked stimulated release was greatest. No changes in dopamine were observed where nonphasic neurons were recorded. Thus, although differences are evident in dopamine release dynamics relative to cocaine-reinforced responding within the core and shell, dopamine release is heterogeneous within each structure and varies as a function of precise neuronal targets during cocaine-seeking behavior.
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118
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Li MD, Tseng WL, Cheng TL. Ultrasensitive detection of indoleamines by combination of nanoparticle-based extraction with capillary electrophoresis/laser-induced native fluorescence. J Chromatogr A 2009; 1216:6451-8. [DOI: 10.1016/j.chroma.2009.07.034] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/11/2009] [Accepted: 07/17/2009] [Indexed: 11/15/2022]
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119
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Ethanol-induced hyperactivity is associated with hypodopaminergia in the 22-TNJ ENU-mutated mouse. Alcohol 2009; 43:421-31. [PMID: 19801272 DOI: 10.1016/j.alcohol.2009.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 04/22/2009] [Accepted: 04/29/2009] [Indexed: 11/23/2022]
Abstract
Characterization of neurochemical and behavioral responses to ethanol in phenotypically distinct mouse strains can provide insight into the mechanisms of ethanol stimulant actions. Increases in striatal dopamine (DA) levels have often been linked to ethanol-induced hyperactivity. We examined the functional status of the DA system and behavioral responsiveness to ethanol, cocaine, and a DA-receptor agonist in an N-ethyl-N-nitrosourea-mutagenized mouse strain, 22-TNJ, generated by the Integrative Neuroscience Initiative on Alcoholism Consortium. The 22-TNJ mouse strain exhibited greater locomotor responses to 2.25g/kg ethanol and 10mg/kg cocaine, compared with control mice. In vivo microdialysis showed low-baseline DA levels and a larger DA increase with both 2.25g/kg ethanol and 10mg/kg cocaine. In in vitro voltammetry studies, the 22-TNJ mice displayed increased V(max) rates for DA uptake, possibly contributing to the low-baseline DA levels found with microdialysis. Finally, 22-TNJ mice showed enhanced in vitro autoreceptor sensitivity to the D2/D3 agonist, quinpirole, and greater locomotor responses to both autoreceptor-selective and postsynaptic receptor-selective doses of apomorphine compared with controls. Taken together, these results indicate that the dopaminergic system of the 22-TNJ mouse is low functioning compared with control, with consequent receptor supersensitivity, such that mutant animals exhibit enhanced behavioral responses to DA-activating drugs, such as ethanol. Thus, the 22-TNJ mouse represents a model for a relatively hypodopaminergic system, and could provide important insights into the mechanisms of hyper-responsiveness to ethanol's stimulant actions.
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120
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Roham M, Halpern JM, Martin HB, Chiel HJ, Mohseni P. Wireless amperometric neurochemical monitoring using an integrated telemetry circuit. IEEE Trans Biomed Eng 2009; 55:2628-34. [PMID: 18990633 DOI: 10.1109/tbme.2008.2001264] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An integrated circuit for wireless real-time monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting high-resolution amperometric measurements in four settings of the input current. The chip architecture includes a first-order Delta Sigma modulator (Delta Sigma M) and a frequency-shift-keyed (FSK) voltage-controlled oscillator (VCO) operating near 433 MHz. It is fabricated using the AMI 0.5 microm double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. Measured dc current resolutions of approximately 250 fA, approximately 1.5 pA, approximately 4.5 pA, and approximately 17 pA were achieved for input currents in the range of +/-5, +/-37, +/-150, and +/-600 nA, respectively. The chip has been interfaced with a diamond-coated, quartz-insulated, microneedle, tungsten electrode, and successfully recorded dopamine concentration levels as low as 0.5 microM wirelessly over a transmission distance of approximately 0.5 m in flow injection analysis experiments.
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Affiliation(s)
- Masoud Roham
- Electrical Engineering and Computer Science Department, Case Western Reserve University, Cleveland, OH 44106, USA
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121
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122
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Shang F, Zhou L, Mahmoud KA, Hrapovic S, Liu Y, Moynihan HA, Glennon JD, Luong JHT. Selective nanomolar detection of dopamine using a boron-doped diamond electrode modified with an electropolymerized sulfobutylether-beta-cyclodextrin-doped poly(N-acetyltyramine) and polypyrrole composite film. Anal Chem 2009; 81:4089-98. [PMID: 19382752 DOI: 10.1021/ac900368m] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-acetyltyramine was synthesized and electropolymerized together with a negatively charged sulfobutylether-beta-cyclodextrin on a boron-doped diamond (BDD) electrode followed by the electropolymerization of pyrrole to form a stable and permselective film for selective dopamine detection. The selectivity and sensitivity of the formed layer-by-layer film was governed by the sequence of deposition and the applied potential. Raman results showed a decrease in the peak intensity at 1329 cm(-1) (sp(3)), the main feature of BDD, upon each electrodeposition step. Such a decrease was correlated well with the change of the charge-transfer resistance derived from impedance data, i.e., reflecting the formation of the layer-by-layer film. The polycrystalline BDD surface became more even with lower surface roughness as revealed by scanning electron and atomic force microscopy. The modified BDD electrode exhibited rapid response to dopamine within 1.5-2 s and a low detection limit of 4-5 nM with excellent reproducibility. Electroactive interferences caused by 4-dihydroxyphenylalanine, 3,4-dihydroxyphenylacetic acid, ascorbic acid, and uric acid were completely eliminated, whereas the signal response of epinephrine and norepinephrine was significantly suppressed by the permselective film.
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Affiliation(s)
- Fengjun Shang
- Analytical and Biological Chemistry Research Facility, Department of Chemistry, University College Cork, Cork, Ireland
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123
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Prabakar S, Narayanan S. Catalytic Oxidation of Dopamine at a Nickel Hexacyanoferrate Surface Modified Graphite Wax Composite Electrode Coated with Nafion. ELECTROANAL 2009. [DOI: 10.1002/elan.200804527] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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124
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Li Y, Bergman D, Zhang B. Preparation and Electrochemical Response of 1−3 nm Pt Disk Electrodes. Anal Chem 2009; 81:5496-502. [DOI: 10.1021/ac900777n] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yongxin Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - David Bergman
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
| | - Bo Zhang
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700
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125
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Chang CY, Takahashi Y, Murata T, Shiku H, Chang HC, Matsue T. Entrapment and measurement of a biologically functionalized microbead with a microwell electrode. LAB ON A CHIP 2009; 9:1185-1192. [PMID: 19370235 DOI: 10.1039/b817705h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A chip with integrated electrophoretic and electrochemical systems was developed to manipulate either an individual microbead or a cell inside a microwell electrode (MWE) for electrochemical measurement. The optimal MWE geometry (30 microm diameter and 25 microm depth) was designed to accommodate the micro particles according to the simulated results. A chip device was sequentially built from a slide patterned with Pt electrodes, an adhesive tape defined with a flow channel (200 microm in width and 25 microm in height), and an indium tin oxide (ITO) cover. The MWE not only generated an active electrophoretic force to trap the particle but also provided a low flow velocity area (LFVA) to stabilize the trapped bead or cell in a continuous flow. Scanning electrochemical microscopy (SECM) theory was employed to explain the electrochemical behaviors of the MWE. An enhanced current was confirmed as the redox recycling effect on the conductive ITO cover. The catalytic reaction of an individual alkaline phosphatase coated microbead (ALP-bead) was electrochemically detected with the MWE after being trapped. The ALP on the trapped ALP-bead catalyzed the hydrolysis of p-aminophenylphosphate (PAPP) to p-aminophenol (PAP), and then a decaying amperogram (+0.3 V vs. Ag/AgCl) due to a tiny PAP quantity around the MWE was observed.
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Affiliation(s)
- Ching-Yu Chang
- Institute of Biomedical Engineering, National Cheng Kung University, Tainan, 701, Taiwan, ROC
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126
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Li X, Hoffman AF, Peng XQ, Lupica CR, Gardner EL, Xi ZX. Attenuation of basal and cocaine-enhanced locomotion and nucleus accumbens dopamine in cannabinoid CB1-receptor-knockout mice. Psychopharmacology (Berl) 2009; 204:1-11. [PMID: 19099297 PMCID: PMC3729960 DOI: 10.1007/s00213-008-1432-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 12/01/2008] [Indexed: 11/24/2022]
Abstract
RATIONALE Effect of cannabinoid CB1 receptor deletion on cocaine's actions is controversial. This is partly based on findings in CB1-receptor-knockout (CB1(-/-)) mice with CD1 genetic background. OBJECTIVES In the present study, we used CB1(-/-) mice with a C57BL/6J genetic background to further investigate the role of CB1 receptors in cocaine's action. MATERIALS AND METHODS Locomotor activity was assessed using AccuScan locomotor chambers. Brain extracellular dopamine (DA) levels were measured by in vivo microdialysis and by fast-scan cyclic voltammetry in the nucleus accumbens (NAc). RESULTS CB1(-/-) mice displayed a significant reduction in basal levels of locomotion and extracellular DA, as well as in cocaine-enhanced locomotion and extracellular DA, as compared to their wild-type (CB1(+/+)) littermates. The reduction in basal and cocaine-enhanced DA appears to be related to a reduction in basal DA release, not to an increase in DA clearance, as indicated by fast-scan cyclic voltammetry in brain slices. Pharmacological blockade of CB1 receptors by SR141716 inhibited locomotion and NAc DA release in CB1(+/+) mice. CONCLUSIONS The present findings suggest an important role for CB1 receptors in mediating cocaine's behavioral and neurochemical effects.
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Affiliation(s)
- Xia Li
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Alexander F. Hoffman
- Neurophysiology Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore MD 21224 USA
| | - Xiao-Qing Peng
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Carl R. Lupica
- Neurophysiology Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore MD 21224 USA
| | - Eliot L. Gardner
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Zheng-Xiong Xi
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
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127
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128
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Jin GP, Peng X, Ding YF. The electrochemical modification of clenbuterol for biosensors of dopamine, norepinephrine, adrenalin, ascorbic acid and uric acid at paraffin-impregnated graphite electrode. Biosens Bioelectron 2008; 24:1037-41. [DOI: 10.1016/j.bios.2008.06.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 06/16/2008] [Accepted: 06/16/2008] [Indexed: 11/28/2022]
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129
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Santos RM, Lourenço CF, Piedade AP, Andrews R, Pomerleau F, Huettl P, Gerhardt GA, Laranjinha J, Barbosa RM. A comparative study of carbon fiber-based microelectrodes for the measurement of nitric oxide in brain tissue. Biosens Bioelectron 2008; 24:704-9. [DOI: 10.1016/j.bios.2008.06.034] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 06/03/2008] [Accepted: 06/23/2008] [Indexed: 10/21/2022]
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130
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Adams KL, Puchades M, Ewing AG. In Vitro Electrochemistry of Biological Systems. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2008; 1:329. [PMID: 20151038 PMCID: PMC2819529 DOI: 10.1146/annurev.anchem.1.031207.113038] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This article reviews recent work involving electrochemical methods for in vitro analysis of biomolecules, with an emphasis on detection and manipulation at and of single cells and cultures of cells. The techniques discussed include constant potential amperometry, chronoamperometry, cellular electroporation, scanning electrochemical microscopy, and microfluidic platforms integrated with electrochemical detection. The principles of these methods are briefly described, followed in most cases with a short description of an analytical or biological application and its significance. The use of electrochemical methods to examine specific mechanistic issues in exocytosis is highlighted, as a great deal of recent work has been devoted to this application.
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Affiliation(s)
- Kelly L. Adams
- Pennsylvania State University, Department of Chemistry, University Park, Pennsylvania 16802
- Göteborg University, Department of Chemistry, SE-412 96 Göteborg, Sweden
| | - Maja Puchades
- Göteborg University, Department of Chemistry, SE-412 96 Göteborg, Sweden
| | - Andrew G. Ewing
- Pennsylvania State University, Department of Chemistry, University Park, Pennsylvania 16802
- Göteborg University, Department of Chemistry, SE-412 96 Göteborg, Sweden
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131
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Robinson DL, Hermans A, Seipel AT, Wightman RM. Monitoring rapid chemical communication in the brain. Chem Rev 2008; 108:2554-84. [PMID: 18576692 PMCID: PMC3110685 DOI: 10.1021/cr068081q] [Citation(s) in RCA: 449] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Donita L Robinson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
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132
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España RA, Roberts DCS, Jones SR. Short-acting cocaine and long-acting GBR-12909 both elicit rapid dopamine uptake inhibition following intravenous delivery. Neuroscience 2008; 155:250-7. [PMID: 18597947 DOI: 10.1016/j.neuroscience.2008.05.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/07/2008] [Accepted: 05/13/2008] [Indexed: 11/24/2022]
Abstract
The rewarding effects of cocaine have been reported to occur within seconds of administration. Extensive evidence suggests that these actions involve the ability of cocaine to inhibit the dopamine (DA) transporter. We recently showed that 1.5 mg/kg i.v. cocaine inhibits DA uptake within 5 s. Despite this evidence, there remains a lack of consensus regarding how quickly i.v. cocaine and other DA uptake inhibitors elicit DA uptake inhibition. The current studies sought to better characterize the onset of cocaine-induced DA uptake inhibition and to compare these effects to those obtained with the high-affinity, long-acting DA transporter inhibitor, GBR-12909 (1-(2-bis(4-fluorphenyl)-methoxy)-ethyl)-4-(3-phenyl-propyl)piperazine). Using in vivo fast scan cyclic voltammetry, we showed that i.v. cocaine (0.75, 1.5, and 3.0 mg/kg) significantly inhibited DA uptake in the nucleus accumbens of anesthetized rats within 5 s. DA uptake inhibition peaked at 30 s and returned to baseline levels in approximately 1 h. The effects of cocaine were dose-dependent, with the 3.0 mg/kg dose producing greater uptake inhibition at the early time points and exhibiting a longer latency to return to baseline. Further, the blood-brain barrier impermeant cocaine-methiodide had no effect on DA uptake or peak height, indicating that the generalized peripheral effects of cocaine do not contribute to the CNS alterations measured here. Finally, we show that GBR-12909 (0.75, 1.5, and 3.0 mg/kg) also significantly inhibited DA uptake within 5 s post-injection, although the peak effect and return to baseline were markedly delayed compared with cocaine, particularly at the highest dose. Combined, these observations indicate that the central effects of dopamine uptake inhibitors occur extremely rapidly following i.v. drug delivery.
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Affiliation(s)
- R A España
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
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133
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Amatore C, Arbault S, Guille M, Lemaître F. Electrochemical Monitoring of Single Cell Secretion: Vesicular Exocytosis and Oxidative Stress. Chem Rev 2008; 108:2585-621. [DOI: 10.1021/cr068062g] [Citation(s) in RCA: 316] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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134
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Walker QD, Kuhn CM. Cocaine increases stimulated dopamine release more in periadolescent than adult rats. Neurotoxicol Teratol 2008; 30:412-8. [PMID: 18508233 DOI: 10.1016/j.ntt.2008.04.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 03/25/2008] [Accepted: 04/15/2008] [Indexed: 11/17/2022]
Abstract
The neural mechanisms responsible for the enhanced adolescent vulnerability for initiating drug abuse are unclear. We investigated whether age differences in dopamine neurotransmission could explain cocaine's enhanced psychomotor effects in the periadolescent rat. Electrical stimulation of the medial forebrain bundle of anesthetized post-natal age 28 days (PN28) and PN65 rats elicited dopamine release in caudate nucleus and nucleus accumbens core before and after 15 mg/kg cocaine i.p. Extracellular dopamine concentrations were greater in PN65 than PN28 caudate following 20 and 60 Hz stimulations and in the PN65 nucleus accumbens following 60 Hz stimulations. Cocaine increased dopamine concentrations elicited by 20 Hz stimulations 3-fold in the adult, but almost 9-fold in periadolescent caudate. Dopamine release rate was lower in the periadolescent caudate although total dopamine clearance was similar to that of adults. The periadolescent caudate achieved adult levels of clearance by compensating for a lower V(max) with higher uptake affinity. Tighter regulation of extracellular dopamine by the higher uptake/release ratio in periadolescents led to greater increases after cocaine. In nucleus accumbens, dopamine release and V(max) were lower in periadolescents than adults, but uptake affinity and cocaine effects were similar. Immaturity of dopamine neurotransmission in dorsal striatum may underlie enhanced acute responses to psychostimulants in adolescent rats and suggests a mechanism for the greater vulnerability of adolescent humans to drug addiction.
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Affiliation(s)
- Q David Walker
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, United States
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135
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Roham M, Daberkow DP, Ramsson ES, Covey DP, Pakdeeronachit S, Garris PA, Mohseni P. A Wireless IC for Wide-Range Neurochemical Monitoring Using Amperometry and Fast-Scan Cyclic Voltammetry. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2008; 2:3-9. [PMID: 23852628 DOI: 10.1109/tbcas.2008.918282] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An integrated circuit for real-time wireless monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting measurements in both fast-scan cyclic voltammetry (FSCV) and amperometry modes for a wide input current range. The chip architecture employs a second-order DeltaSigma modulator (DeltaSigmaM) and a frequency-shift-keyed transmitter operating near 433 MHz. It is fabricated using the AMI 0.5-mum double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. A measured current resolution of 12 pA at a sampling rate of 100 Hz and 132 pA at a sampling rate of 10 kHz is achieved in amperometry and 300-V/s FSCV modes, respectively, for any input current in the range of plusmn430 nA. The modulator core and the transmitter draw 22 and 400 muA from a 2.6-V power supply, respectively. The chip has been externally interfaced with a carbon-fiber microelectrode implanted acutely in the caudate-putamen of an anesthetized rat, and, for the first time, extracellular levels of dopamine elicited by electrical stimulation of the medial forebrain bundle have been successfully recorded wirelessly using 300-V/s FSCV.
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136
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Wolfrum B, Zevenbergen M, Lemay S. Nanofluidic Redox Cycling Amplification for the Selective Detection of Catechol. Anal Chem 2008; 80:972-7. [PMID: 18193890 DOI: 10.1021/ac7016647] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bernhard Wolfrum
- Kavli Institute of Nanoscience, Section Molecular Biophysics, Technical University Delft, Delft, 2628 CJ, The Netherlands
| | - Marcel Zevenbergen
- Kavli Institute of Nanoscience, Section Molecular Biophysics, Technical University Delft, Delft, 2628 CJ, The Netherlands
| | - Serge Lemay
- Kavli Institute of Nanoscience, Section Molecular Biophysics, Technical University Delft, Delft, 2628 CJ, The Netherlands
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137
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Abstract
Single-cell amperometry is a powerful tool for the study of the mechanisms underlying secretion from cells that release electrochemically active substances like catecholamines, histamine, or serotonin. Amperometry has changed our view of the secretory process and the quantal release phenomenon. Today, it is a relatively easy technique to set up and affordable for most laboratories. Amperometry can help solve many interesting problems in cell physiology or pharmacology. However, there are a number of issues about the experimental design, data analysis, and result interpretation that need to be considered. Here, we compile some recommendations and advice on how to conduct experiments with amperometry, covering tissue culture, electrode types and their construction, calibration, equipment, data acquisition, and strategies for electrical noise reduction. We concentrate on cultured chromaffin cells, although most of the information is equally applicable to other cell types.
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Affiliation(s)
- David J Machado
- Pharmacology Unit, Faculty of Medicine, University of La Laguna, Tenerife, Spain
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138
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Aspartame decreases evoked extracellular dopamine levels in the rat brain: An in vivo voltammetry study. Neuropharmacology 2007; 53:967-74. [DOI: 10.1016/j.neuropharm.2007.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 09/19/2007] [Accepted: 09/20/2007] [Indexed: 11/22/2022]
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139
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Suzuki A, Ivandini TA, Yoshimi K, Fujishima A, Oyama G, Nakazato T, Hattori N, Kitazawa S, Einaga Y. Fabrication, Characterization, and Application of Boron-Doped Diamond Microelectrodes for in Vivo Dopamine Detection. Anal Chem 2007; 79:8608-15. [DOI: 10.1021/ac071519h] [Citation(s) in RCA: 193] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akane Suzuki
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Tribidasari A. Ivandini
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Kenji Yoshimi
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Akira Fujishima
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Genko Oyama
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Taizo Nakazato
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Nobutaka Hattori
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Shigeru Kitazawa
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
| | - Yasuaki Einaga
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan, Chemistry Department, Faculty of Mathematics and Science, University of Indonesia, Kampus Baru UI Depok, Jakarta 16-424, Indonesia, Department of Neurology, Medical School, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, Kanagawa Academy of Science and Technology, KSP 3-2-1 Sakado, Kawasaki 213-0012, Japan, Department of Neurophysiology, School of Medicine, Juntendo
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140
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Ates M, Castillo J, Sezai Sarac A, Schuhmann W. Carbon fiber microelectrodes electrocoated with polycarbazole and poly(carbazole-co-p-tolylsulfonyl pyrrole) films for the detection of dopamine in presence of ascorbic acid. Mikrochim Acta 2007. [DOI: 10.1007/s00604-007-0837-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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141
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Chen YH, Harvey BK, Hoffman AF, Wang Y, Chiang YH, Lupica CR. MPTP-induced deficits in striatal synaptic plasticity are prevented by glial cell line-derived neurotrophic factor expressed via an adeno-associated viral vector. FASEB J 2007; 22:261-75. [PMID: 17690153 DOI: 10.1096/fj.07-8797com] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study determined the consequences of dopamine denervation of the striatum on synaptic plasticity and prevention of these changes with gene therapy using an adeno-associated viral vector (AAV) expressing glial cell line-derived neurotrophic factor (GDNF). C57BL6/J mice were injected with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP); long-term depression (LTD) or potentiation (LTP) were measured in vitro. Fast-scan cyclic voltammetry measured electrically released dopamine from a functionally relevant pool in these same striatal slices. After MPTP, dopamine release and uptake were greatly diminished, and LTP and LTD were blocked in the striatal slices. The loss of plasticity resulted directly from the loss of dopamine since its application rescued synaptic plasticity. Striatal GDNF expression via AAV, before MPTP, significantly protected against the loss of dopamine and prevented the blockade of corticostriatal LTP. These data demonstrate that dopamine plays a role in supporting several forms of striatal plasticity and that GDNF expression via AAV prevents the loss of dopamine and striatal plasticity caused by MPTP. We propose that impairment of striatal plasticity after dopamine denervation plays a role in the symptomology of Parkinson's disease and that AAV expression of neurotrophic factors represents a tenable approach to protecting against or slowing these neurobiological deficits.
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Affiliation(s)
- Yuan-Hao Chen
- Program of Clinical Medicine, Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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142
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Kato D, Xu G, Iwasaki Y, Hirata Y, Kurita R, Niwa O. Heavy phosphate adsorption on amorphous ITO film electrodes: nano-barrier effect for highly selective exclusion of anionic species. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8400-5. [PMID: 17616215 DOI: 10.1021/la700466y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We prepared an amorphous indium tin oxide (ITO) film and studied it with respect to its surface characterization and the effect of phosphate adsorption on its electrochemical properties. The film was deposited using RF sputtering under ambient low-oxygen conditions at room temperature. The XPS results revealed that the amount of phosphate adsorbed on the amorphous ITO film was more than 4.6 times greater than that adsorbed on commercially available polycrystalline ITO film in spite of the smaller microscopic surface area of the former. Electrochemical responses for anionic species such as L-ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC) on the phosphate-adsorbed ITO film electrodes were more effectively suppressed at the amorphous ITO film electrode than at the polycrystalline ITO film electrode when a phosphate-containing electrolyte was used. Such suppression could be attributed to the electrostatic repulsion between the anionic species and more heavily adsorbed phosphate on our amorphous ITO film electrode surface. This effect is made more pronounced by increasing the phosphate concentration to 1 mM. With 1 mM phosphate, the amorphous ITO film electrode showed the highest selectivity for dopamine (DA) against the anionic species, namely, 880 for DA/AA and 330 for DA/DOPAC, respectively. In contrast, the selectivity was 120 for DA/AA and 20 for DA/DOPAC with the polycrystalline ITO film electrode.
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Affiliation(s)
- Dai Kato
- National Institute of Advanced Industrial Science and Technology, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
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143
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Swamy BEK, Venton BJ. Carbon nanotube-modified microelectrodes for simultaneous detection of dopamine and serotonin in vivo. Analyst 2007; 132:876-84. [PMID: 17710262 DOI: 10.1039/b705552h] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dopamine and serotonin are important neurotransmitters that interact in the brain. While dopamine is easily detected with electrochemical sensors, the detection of serotonin is more difficult because reactive species formed after oxidation can adsorb to the electrode, reducing sensitivity. Carbon nanotube treatments of electrodes have been used to increase the sensitivity, promote electron transfer, and reduce fouling. Most methods have focused on nanotube coatings of large electrodes and slower electrochemical techniques that are not conducive to measurements in vivo. In this study, we investigated carbon-fiber microelectrodes modified with single-walled carbon nanotubes for the co-detection of dopamine and serotonin in vivo. Using fast-scan cyclic voltammetry, S/N ratios for the neurotransmitters increased after nanotube coating. Electrocatalytic effects of nanotubes were not apparent at fast scan rates but faster kinetics were observed with slower scanning. Nanotube-modified microelectrodes showed significantly less fouling after exposure to serotonin than bare electrodes. The nanotube-modified electrodes were used to monitor stimulated dopamine and serotonin changes simultaneously in the striatum of anesthetized rat after administration of a serotonin synthetic precursor. These studies show that nanotube-coated microelectrodes can be used with fast scanning techniques and are advantageous for in vivo measurements of neurotransmitters because of their greater sensitivity and resistance to fouling.
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Affiliation(s)
- B E Kumara Swamy
- Dept. of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, VA 22904-4319, USA
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144
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Lambie BA, Brennan C, Olofsson J, Orwar O, Weber SG. Experimentally determining the iR drop in solution at carbon fiber microelectrodes with current interruption and application to single-cell electroporation. Anal Chem 2007; 79:3771-8. [PMID: 17411009 PMCID: PMC2529252 DOI: 10.1021/ac062045+] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-cell electroporation uses microelectrodes, capillaries, or micropipets positioned near single, adherent cells to increase transiently the membrane permeability of the cell. The increased permeability permits, for example, transfection without chemical reagents. When using microelectrodes to apply an electric field to the cell, there is a question of how much voltage to apply. Unlike in bulk electroporation, where hundreds of volts may be applied between electrodes, a rather small voltage is applied to a microelectrode in single-cell electroporation. In the single-cell experiment with microelectrodes, a substantial fraction of the voltage is lost at the interface and does not therefore exist in solution. This problem is the same as the classical electrochemist's problem of knowing the "iR" drop in solution and correcting for it to obtain true interfacial potential differences. Therefore, we have used current interruption to determine the iR drop in solution near microcylinder electrodes. As the field is inhomogeneous, calculations are required to understand the field distribution. Results of the current interruption are validated by comparing two independent measurements of the resistance in solution: one value results from the measured iR drop in conjunction with the known applied current. The other value results from a measured solution conductivity and a computed cell constant. We find substantial agreement in the range of resistances from about 2 to 50 kOmega, but not at higher resistances. We propose a simple, four-step plan that takes a few minutes to calculate the approximate current required to electroporate a cell with an electrode of a particular size, shape, and distance from the cell. We validate the approach with electroporation of single A549 cells.
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Affiliation(s)
- Bradley A Lambie
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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145
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Li G, Abdel-Rahman AA. Direct evidence for imidazoline (I1) receptor modulation of ethanol action on norepinephrine-containing neurons in the rostral ventrolateral medulla in conscious spontaneously hypertensive rats. Alcohol Clin Exp Res 2007; 31:684-93. [PMID: 17374048 DOI: 10.1111/j.1530-0277.2007.00353.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Enhancement of the rostral ventrolateral medulla (RVLM) presympathetic (norepinephrine, NE) neuronal activity represents a neurochemical mechanism for the pressor effect of ethanol. In this study, we tested the hypothesis that ethanol action on RVLM presympathetic neurons is selectively influenced by the signaling of the local imidazoline (I1) receptor. To support a neuroanatomical and an I1-signaling selectivity of ethanol, and to circumvent the confounding effects of anesthesia, the dose-related neurochemical and blood pressure effects of ethanol were investigated in the presence of selective pharmacological interventions that cause reduction in the activity of RVLM or nucleus tractus solitarius (NTS) NE neurons via local activation of the I1 or the alpha2-adrenergic receptor in conscious spontaneously hypertensive rats. RESULTS Local activation of the I1 receptor by rilmenidine (40 nmol) or by the I1/alpha2 receptor mixed agonist clonidine (1 nmol), and local activation of the alpha2-adrenergic receptor (alpha2AR) by the pure alpha2AR agonist alpha-methylnorepinephrine (alpha-MNE, 10 nmol) caused reductions in RVLM NE, and blood pressure. Intra-RVLM ethanol (1, 5, or 10 microg), microinjected at the nadir of the neurochemical and hypotensive responses, elicited dose-dependent increments in RVLM NE and blood pressure in the presence of local I1--but not alpha2-receptor activation. Only intra-NTS alpha-MNE, but not rilmenidine or clonidine, elicited reductions in local NE and blood pressure; ethanol failed to elicit any neurochemical or blood pressure responses in the presence of local activation of the alpha2AR within the NTS. CONCLUSION The findings support the neuroanatomical selectivity of ethanol, and support the hypothesis that the neurochemical (RVLM NE), and the subsequent cardiovascular, effects of ethanol are selectively modulated by I1 receptor signaling in the RVLM.
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Affiliation(s)
- Guichu Li
- Department of Pharmacology and Toxicology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27858, USA
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146
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Braun T, Voland P, Kunz L, Prinz C, Gratzl M. Enterochromaffin cells of the human gut: sensors for spices and odorants. Gastroenterology 2007; 132:1890-901. [PMID: 17484882 DOI: 10.1053/j.gastro.2007.02.036] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 01/30/2007] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Release of serotonin from mucosal enterochromaffin cells triggered by luminal substances is the key event in the regulation of gut motility and secretion. We were interested to know whether nasal olfactory receptors are also expressed in the human gut mucosa by enterochromaffin cells and whether their ligands and odorants present in spices, fragrances, detergents, and cosmetics cause serotonin release. METHODS Receptor expression was studied by the reverse-transcription polymerase chain reaction method in human mucosal enterochromaffin cells isolated by laser microdissection and in a cell line derived from human enterochromaffin cells. Activation of the cells by odorants was investigated by digital fluorescence imaging using the fluorescent Ca(2+) indicator Fluo-4. Serotonin release was measured in culture supernatants by a serotonin enzyme immunoassay and amperometry using carbon fiber microelectrodes placed on single cells. RESULTS We found expression of 4 olfactory receptors in microdissected human mucosal enterochromaffin cells and in a cell line derived from human enterochromaffin cells. Ca(2+) imaging studies revealed that odorant ligands of the identified olfactory receptors cause Ca(2+) influx, elevation of intracellular free Ca(2+) levels, and, consequently, serotonin release. CONCLUSIONS Our results show that odorants present in the luminal environment of the gut may stimulate serotonin release via olfactory receptors present in human enterochromaffin cells. Serotonin controls both gut motility and secretion and is implicated in pathologic conditions such as vomiting, diarrhea, and irritable bowel syndrome. Thus, olfactory receptors are potential novel targets for the treatment of gastrointestinal diseases and motility disorders.
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Affiliation(s)
- Thomas Braun
- Institute of Anatomy, Ludwig Maximilian University Munich, Munich, Germany
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147
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Osbourn DM, Sanger RH, Smith PJS. Determination of single-cell oxygen consumption with impedance feedback for control of sample-probe separation. Anal Chem 2007; 77:6999-7004. [PMID: 16255601 DOI: 10.1021/ac050326w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to measure chemical gradients surrounding single cells provides novel insights into several areas of cell dynamics--particularly metabolism. Detection of metabolic oxygen consumption can be achieved from a single mammalian cell using a modulated amperometric sensor in a self-referencing mode. To date, however, apart from visual cues, we do not have a reliable and cell-compatible method for determining and stabilizing the position of such probes. In this paper, we report on having successfully measured the increase in the uncompensated resistance of an electrochemical cell upon approach to single, living, biological cells, while simultaneously measuring the metabolic oxygen consumption. This was accomplished by applying an ac and a dc excitation signal to the electrode. The applied ac waveform was a 100-kHz sine wave with an amplitude of 10 mV rms, while the dc voltage applied was -600 mV. The two signals were shown not to interfere with one another. Furthermore, it is shown that the sample-probe distance can be measured for approach to single cells on the order of 10-15-microm diameter and 5-microm height, with 100-nm resolution.
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Affiliation(s)
- Damon M Osbourn
- Program in Molecular Physiology, Marine Biological Laboratory, BioCurrents Research Center, Woods Hole, Massachusetts 02543, USA
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148
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John CE, Jones SR. Voltammetric characterization of the effect of monoamine uptake inhibitors and releasers on dopamine and serotonin uptake in mouse caudate-putamen and substantia nigra slices. Neuropharmacology 2007; 52:1596-605. [PMID: 17459426 PMCID: PMC2041899 DOI: 10.1016/j.neuropharm.2007.03.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 02/28/2007] [Accepted: 03/07/2007] [Indexed: 11/23/2022]
Abstract
Fast scan cyclic voltammetry is an electrochemical technique used to measure dynamics of transporter-mediated monoamine uptake in real time and provides a tool to evaluate the detailed effects of monoamine uptake inhibitors and releasers on dopamine and serotonin transporter function. We measured the effects of cocaine, methylphenidate, 2beta-propanoyl-3beta-(4tolyl) tropane (PTT), fluoxetine, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), phentermine and fenfluramine on dopamine and serotonin uptake following electrically stimulated release in mouse caudate-putamen and substantia nigra pars reticulata slices. We determined rank orders of uptake inhibition effects based on two variables; increases in apparent K(m) for dopamine and serotonin uptake and inhibition constant (K(i)) values. For example, the rank order of uptake inhibition based on apparent K(m) values at the dopamine transporter was amphetamine>or=PTT>or=methylphenidate>>methamphetamine=phentermine=MDMA>cocaine>>fluoxetine=fenfluramine, and at the serotonin transporter was fluoxetine=methamphetamine=fenfluramine=MDMA > amphetamine=cocaine=PTT>or=methylphenidate>phentermine. Additionally, changes in electrically stimulated release were documented. This is the first study using voltammetry to measure the effects of a wide range of monoamine uptake inhibitors and releasers on dopamine and serotonin uptake in mouse brain slices. These studies also highlight methodological considerations for comparison of effects between heterogeneous brain regions.
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Affiliation(s)
- Carrie E. John
- Wake Forest University School of Medicine, Department of Physiology and Pharmacology, Medical Center Boulevard, Winston-Salem, NC 27157
| | - Sara R. Jones
- Wake Forest University School of Medicine, Department of Physiology and Pharmacology, Medical Center Boulevard, Winston-Salem, NC 27157
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149
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Hayashi K, Iwasaki Y, Horiuchi T, Sunagawa K, Tate A. Selective detection of a catecholamine against electroactive interferents using an interdigitated heteroarray electrode consisting of a metal oxide electrode and a metal band electrode. Anal Chem 2007; 77:5236-42. [PMID: 16097764 DOI: 10.1021/ac050216p] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We developed an interdigitated array electrode (IDAE) consisting of a metal oxide electrode and a metal band heteroelectrode and employed it for the selective detection of catecholamines. We used an indium-tin oxide (ITO) film as the oxidation electrode of the IDAE because the ITO was able to suppress response currents from L-ascorbic acid (AA) and uric acid (UA), which are major electroactive interferents in biological fluids. However, the ITO film also suppresses the reduction of quinones including oxidized catecholamines. We developed a simple technique for fabricating our hetero IDAE, which also preserves the electrochemical properties of the ITO. When we compared hetero ITO-gold, homo ITO-ITO, and carbon-carbon IDAEs, we found that the hetero IDAE provided both high sensitivity and selectivity for DA detection. We achieved high selectivities for DA against AA and UA. The ratios of the response currents of AA and UA to DA were calculated as 6 and 5%, respectively.
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Affiliation(s)
- Katsuyoshi Hayashi
- NTT Microsystem Integration Laboratories, 3-1 Morinosato, Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
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150
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Xiang L, Lin Y, Yu P, Su L, Mao L. Laccase-catalyzed oxidation and intramolecular cyclization of dopamine: A new method for selective determination of dopamine with laccase/carbon nanotube-based electrochemical biosensors. Electrochim Acta 2007. [DOI: 10.1016/j.electacta.2006.11.040] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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