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Wei W, Song Y, Shi W, Lin N, Jiang T, Cai X. A high sensitivity MEA probe for measuring real time rat brain glucose flux. Biosens Bioelectron 2013; 55:66-71. [PMID: 24362080 DOI: 10.1016/j.bios.2013.11.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 11/26/2022]
Abstract
The mammalian central nervous system (CNS) relies on a constant supply of external glucose for its undisturbed operation. This article presents an implantable Multi-Electrode Array (MEA) probe for brain glucose measurement. The MEA was implemented on Silicon-On-Insulator (SOI) wafer using Micro-Electro-Mechanical-Systems (MEMS) methods. There were 16 platinum recording sites on the probe and enzyme glucose oxidase (GOx) was immobilized on them. The glucose sensitivity of the MEA probe was as high as 489 µA mM(-1) cm(-2). 1,3-Phenylenediamine (mPD) was electropolymerized onto the Pt recording surfaces to prevent larger molecules such as ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), and dopamine (DA) from reaching the recording sites surface. The MEA probe was implanted in the anesthetized rat striatum and responded to glucose levels which were altered by intraperitoneal injection of glucose and insulin. After the in vivo experiment, the MEA probe still kept sensitivity to glucose, these suggested that the MEA probe was reliable for glucose monitoring in brain extracellular fluid (ECF).
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Affiliation(s)
- Wenjing Wei
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yilin Song
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China
| | - Wentao Shi
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China
| | - Nansen Lin
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China
| | - Tingjun Jiang
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100190, China
| | - Xinxia Cai
- State Key Laboratory of Transducer Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100190, China.
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Woo DH, Han KS, Shim JW, Yoon BE, Kim E, Bae JY, Oh SJ, Hwang EM, Marmorstein AD, Bae YC, Park JY, Lee CJ. TREK-1 and Best1 channels mediate fast and slow glutamate release in astrocytes upon GPCR activation. Cell 2012; 151:25-40. [PMID: 23021213 DOI: 10.1016/j.cell.2012.09.005] [Citation(s) in RCA: 245] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 06/18/2012] [Accepted: 09/05/2012] [Indexed: 11/28/2022]
Abstract
Astrocytes release glutamate upon activation of various GPCRs to exert important roles in synaptic functions. However, the molecular mechanism of release has been controversial. Here, we report two kinetically distinct modes of nonvesicular, channel-mediated glutamate release. The fast mode requires activation of G(αi), dissociation of G(βγ), and subsequent opening of glutamate-permeable, two-pore domain potassium channel TREK-1 through direct interaction between G(βγ) and N terminus of TREK-1. The slow mode is Ca(2+) dependent and requires G(αq) activation and opening of glutamate-permeable, Ca(2+)-activated anion channel Best1. Ultrastructural analyses demonstrate that TREK-1 is preferentially localized at cell body and processes, whereas Best1 is mostly found in microdomains of astrocytes near synapses. Diffusion modeling predicts that the fast mode can target neuronal mGluR with peak glutamate concentration of 100 μM, whereas slow mode targets neuronal NMDA receptors at around 1 μM. Our results reveal two distinct sources of astrocytic glutamate that can differentially influence neighboring neurons.
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Affiliation(s)
- Dong Ho Woo
- Center for Neural Science, Korea Institute of Science and Technology, Seoul, Republic of Korea
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Stephens ML, Pomerleau F, Huettl P, Gerhardt GA, Zhang Z. Real-time glutamate measurements in the putamen of awake rhesus monkeys using an enzyme-based human microelectrode array prototype. J Neurosci Methods 2009; 185:264-72. [PMID: 19850078 DOI: 10.1016/j.jneumeth.2009.10.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 10/11/2009] [Accepted: 10/11/2009] [Indexed: 11/19/2022]
Abstract
Commonly used for research studies in the central nervous system, microdialysis has revealed a link between dysregulation of the excitatory neurotransmitter glutamate and ischemia and seizure, however limitations like slow temporal resolution have stalled the advancement of microdialysis as a diagnostic tool. We have developed and extensively characterized an enzyme-based microelectrode array technology for second-by-second in vivo amperometric measurements of glutamate in the mammalian CNS. The current studies demonstrated the ability of a human microelectrode array prototype (Spencer-Gerhardt-2 (SG-2)) to measure tonic and phasic glutamate neurotransmission in the putamen of unanesthetized non-human primates. We also showed that the SG-2 remains functional following sterilization. Ability to monitor dynamic changes in glutamate in real-time may assist the development of clinical algorithms to potentially alert care-providers prior to onset of overt ischemia or seizure, or provide neurosurgeons with second-by-second measurements of rapid changes in extracellular glutamate which could help guide surgical procedures or aid in interventional strategies.
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Affiliation(s)
- Michelle L Stephens
- Department of Anatomy and Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536-0098, USA
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Uehara T, Sumiyoshi T, Itoh H, Kurata K. Lactate production and neurotransmitters; evidence from microdialysis studies. Pharmacol Biochem Behav 2008; 90:273-81. [PMID: 18502489 DOI: 10.1016/j.pbb.2008.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 03/22/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
Abstract
Recent studies have found that lactate metabolism plays a significant role in energy supply during acute neural activation in the brain. We will review evidence from microdialysis studies for a relationship between neurotransmitters and lactate production, as revealed in studies of the effects of psychotropic drugs on stress-induced enhancement of extracellular lactate concentrations. Glutamate enhances stress-induced lactate production via activation of N-methyl-D-asparate receptors, and is affected by uptake of glutamate through glutamate transporters. Findings from microdialysis studies suggest that major neurotransmitters, including norepinephrine, dopamine, serotonin, and GABA (via benzodiazepine-receptors) affect lactate production, depending on brain areas, especially during stress. Among these neurotransmitters, glutamate may principally contribute to the regulation of lactate production, with other neurotransmitter systems affecting the extracellular lactate levels in a glutamate-mediated manner. The role for anaerobic metabolism in the supply of energy, as represented by lactate dynamics, deserves further clarification. Monitoring with intracerebral microdialysis is a reliable method for this purpose. Research into this area is likely to provide a novel insight into the mode of action of psychotropic drugs, and the pathophysiology of some of the stress-related mental disorders as well.
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Affiliation(s)
- Takashi Uehara
- Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences, Toyama, Japan.
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Plock N, Kloft C. Microdialysis—theoretical background and recent implementation in applied life-sciences. Eur J Pharm Sci 2005; 25:1-24. [PMID: 15854796 DOI: 10.1016/j.ejps.2005.01.017] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Revised: 01/20/2005] [Accepted: 01/21/2005] [Indexed: 11/26/2022]
Abstract
In the past decade microdialysis has become a method of choice in the study of unbound tissue concentrations of both endogenous and exogenous substances. Microdialysis has been shown to offer information about substances directly at the site of action while being well tolerable and safe. The large variety of its field of application has been demonstrated. However, a few challenges have to be met to make this method generally applicable in routine applications. This review will provide an overview over theoretical aspects that have to be considered during the implementation of microdialysis. Moreover, a comparison between microdialysis and other tissue sampling techniques will demonstrate advantages and limitations of the methods mentioned. Subsequently, it will present a critical synopsis of a variety of scientific/biomedical applications of this method with emphasis on the most recent literature, focussing on target tissues while giving examples of substances examined. It is concluded that microdialysis will be of great value in future investigations of pharmacokinetics, pharmacodynamics and in monitoring of disease status and progression.
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Affiliation(s)
- Nele Plock
- Department of Clinical Pharmacy, Institute of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, D-12169 Berlin, Germany
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Zhang FF, Wan Q, Li CX, Wang XL, Zhu ZQ, Xian YZ, Jin LT, Yamamoto K. Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles. Anal Bioanal Chem 2004; 380:637-42. [PMID: 15517210 DOI: 10.1007/s00216-004-2804-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Revised: 07/15/2004] [Accepted: 07/16/2004] [Indexed: 10/26/2022]
Abstract
An electrochemical method suitable for the simultaneous measurement of cerebral glucose, lactate, L-glutamate and hypoxanthine concentrations from in vivo microdialysis sampling has been successfully performed for the first time using a neutral red-doped silica (NRDS) nanoparticle-derived enzyme sensor system. These uniform NRDS nanoparticles (about 50 +/- 3 nm) were prepared by a water-in-oil (W/O) microemulsion method, and characterized by a TEM technique. The neutral red-doped interior maintained its high electron-activity, while the exterior nano-silica surface prevented the mediator from leaching out into the aqueous solution, and showed high biocompability. These nanoparticles were then mixing with the glucose oxidase (GOD), lactate oxidase (LOD), L-glutamate oxidase (L-GLOD) or xanthine oxidase (XOD), and immobilized on four glassy carbon electrodes, respectively. A thin Nafion film was coated on the enzyme layer to prevent interference from molecules such as ascorbic acid and uric acid in the dialysate. The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum.
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Affiliation(s)
- Fen-Fen Zhang
- Department of Chemistry, East China Normal University, Shanghai 200062, China
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Zhang FF, Wan Q, Wang XL, Sun ZD, Zhu ZQ, Xian YZ, Jin LT, Yamamoto K. Amperometric sensor based on ferrocene-doped silica nanoparticles as an electron transfer mediator for the determination of glucose in rat brain coupled to in vivo microdialysis. J Electroanal Chem (Lausanne) 2004. [DOI: 10.1016/j.jelechem.2004.04.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Galvan A, Smith Y, Wichmann T. Continuous monitoring of intracerebral glutamate levels in awake monkeys using microdialysis and enzyme fluorometric detection. J Neurosci Methods 2003; 126:175-85. [PMID: 12814842 DOI: 10.1016/s0165-0270(03)00092-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A technique for continuous on-line detection of glutamate using brain microdialysis in awake primates is described. The method is based on an enzymatic assay using fluorescence detection of glutamate. The time resolution of the continuous fluorescent readout compares favorably with that of most published studies, which have used standard high-pressure liquid chromatography detection methods for glutamate. Exposure of the system to other amino acids (GABA, aspartate, glutamine, ascorbate, taurine, valine, alanine, and D-glutamate) revealed that this method is highly specific for L-glutamate. In vitro, the system detects reliably glutamate levels as low as 0.5 micromol/l. In vivo testing in the striatum of Rhesus macaques showed that glutamate levels were enhanced after reverse microdialysis with a glutamate uptake blocker. Stimulation with high potassium increased substantially the levels of glutamate, an effect that was calcium-dependent. Glutamate levels were also increased when the microdialysis solution contained the blocker of voltage-gated potassium channels, 4-aminopyridine. This technique effectively detects short-term changes in glutamate levels evoked by physiologic or pharmacologic manipulations in the primate brain.
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Affiliation(s)
- Adriana Galvan
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
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Obrenovitch TP, Urenjak J. Accumulation of Quinolinic Acid With Neuroinflammation: Does It Mean Excitotoxicity? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 527:147-54. [PMID: 15206727 DOI: 10.1007/978-1-4615-0135-0_17] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
The quinolinic acid (QUIN) accumulation that is associated with neuroinflammation is often considered capable of promoting excitotoxic neuronal damage, but QUIN is a relatively weak agonist of N-methyl-D-aspartate (NMDA) receptors. Our study aimed to determine, in vivo, which extracellular concentrations of QUIN must be reached to initiate electrophysiological changes indicative of excitotoxic stress in the cerebral cortex of rats, under normal conditions and when superimposed to a challenge involving NMDA-receptor activation, i.e. repeated cortical spreading depression (CSD). Our experimental strategy relied on microdialysis probes incorporating an electrode, implanted in the brain of halothane-anaesthetised rats. These devices were used to apply QUIN or NMDA locally to the cortical area under study (with or without co-perfusion of high K+ for repetitive induction of CSD), and to record the associated changes in the extracellular DC potential (for information on the membrane polarisation of the cellular population surrounding the probe) and lactate (for the detection of increased local energy demand). The extracellular EC50 for induction of local depolarisation in the normal cortex was around 30 times higher than the extracellular QUIN levels measured in the immunoactivated brain of gerbils. Within the range of concentrations 0.03 to 0.3 mM in the perfusion medium, QUIN suppressed concentration-dependently the elicitation of CSD by K+, presumably because of NMDA-receptor desensitisation. Finally, on-line monitoring of changes in extracellular lactate with local application of QUIN indicated that extracellular concentration of QUIN in the low micromolar range are well tolerated by the brain parenchyma, at least in cortical regions. All these data do not support the notion that QUIN accumulation adds an excitotoxic component to neuroinflammation.
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Affiliation(s)
- Tiho P Obrenovitch
- Pharmacology, School of Pharmacy, University of Bradford, Bradford, BD7 1DP, UK.
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Nedergaard M, Takano T, Hansen AJ. Beyond the role of glutamate as a neurotransmitter. Nat Rev Neurosci 2002; 3:748-55. [PMID: 12209123 DOI: 10.1038/nrn916] [Citation(s) in RCA: 332] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Glutamate is the principal excitatory neurotransmitter of the central nervous system, but many studies have expanded its functional repertoire by showing that glutamate receptors are present in a variety of non-excitable cells. How does glutamate receptor activation modulate their activity? Do non-excitable cells release glutamate, and, if so, how? These questions remain enigmatic. Here, we review the current knowledge on glutamatergic signalling in non-neuronal cells, with a special emphasis on astrocytes.
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Affiliation(s)
- Maiken Nedergaard
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York 10595, USA.
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