1
|
Bade A, Yadav P, Zhang L, Naidu Bypaneni R, Xu M, Glass TE. Imaging Neurotransmitters with Small-Molecule Fluorescent Probes. Angew Chem Int Ed Engl 2024; 63:e202406401. [PMID: 38831475 DOI: 10.1002/anie.202406401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/05/2024]
Abstract
Neurotransmitters play a crucial role in regulating communication between neurons within the brain and central nervous system. Thus, imaging neurotransmitters has become a high priority in neuroscience. This minireview focuses on recent advancements in the development of fluorescent small-molecule fluorescent probes for neurotransmitter imaging and applications of these probes in neuroscience. Innovative approaches for probe design are highlighted as well as attributes which are necessary for practical utility, with a view to inspiring new probe development capable of visualizing neurotransmitters.
Collapse
Affiliation(s)
- Anusha Bade
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| | - Peeyush Yadav
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| | - Le Zhang
- Laboratory of Chemical Immunology and Proteomics, The Rockefeller University, New York NY, 10065, USA
| | | | - Ming Xu
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| | - Timothy E Glass
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| |
Collapse
|
2
|
Shuvaev A, Belozor O, Shuvaev A. Information Load from Neuromediator Diffusion to Extrasynaptic Space: The Interplay between the Injection Frequency and Clearance. BIOLOGY 2024; 13:566. [PMID: 39194504 DOI: 10.3390/biology13080566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 07/15/2024] [Accepted: 07/23/2024] [Indexed: 08/29/2024]
Abstract
In our study, we simulate the release of glutamate, a neurotransmitter, from the presynaptic cell by modeling the diffusion of glutamate into both synaptic and extrasynaptic space around the synapse. We have also incorporated a new factor into our model: convection. This factor represents the process by which the body clears glutamate from the synapse. Due to this process, the physiological mechanisms that typically prevent glutamate from spreading beyond the synapse are altered. This results in a different distribution of glutamate concentrations, with higher levels outside the synapse than inside it. The variety of biological effects that occur in response to this extrasynaptic glutamate highlights the importance of preventing neurotransmitters from spreading beyond the synapse. We aim to explain the physical reasons behind these biological effects, which are observed as excitotoxicity. Our results show that preventing the spread of glutamate outside the synapse increases the amount of information exchanged within the synapse and its surroundings for frequencies of glutamate release up to 30-50 Hz, followed by a decrease. Additionally, we find that the rate at which glutamate is cleared from the synapse is effective at relatively low levels (≤0.5 nm/μs in our calculation grid) and remains constant at higher levels.
Collapse
Affiliation(s)
- Andrey Shuvaev
- Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 660041 Krasnoyarsk, Russia
| | - Olga Belozor
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University, 660022 Krasnoyarsk, Russia
| | - Anton Shuvaev
- Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 660041 Krasnoyarsk, Russia
- Research Institute of Molecular Medicine and Pathobiochemistry, Krasnoyarsk State Medical University, 660022 Krasnoyarsk, Russia
| |
Collapse
|
3
|
Tang C, Todo Y, Kodera S, Sun R, Shimada A, Hirata A. A novel multivariate time series forecasting dendritic neuron model for COVID-19 pandemic transmission tendency. Neural Netw 2024; 179:106527. [PMID: 39029298 DOI: 10.1016/j.neunet.2024.106527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/21/2024] [Accepted: 07/07/2024] [Indexed: 07/21/2024]
Abstract
A novel coronavirus discovered in late 2019 (COVID-19) quickly spread into a global epidemic and, thankfully, was brought under control by 2022. Because of the virus's unknown mutations and the vaccine's waning potency, forecasting is still essential for resurgence prevention and medical resource management. Computational efficiency and long-term accuracy are two bottlenecks for national-level forecasting. This study develops a novel multivariate time series forecasting model, the densely connected highly flexible dendritic neuron model (DFDNM) to predict daily and weekly positive COVID-19 cases. DFDNM's high flexibility mechanism improves its capacity to deal with nonlinear challenges. The dense introduction of shortcut connections alleviates the vanishing and exploding gradient problems, encourages feature reuse, and improves feature extraction. To deal with the rapidly growing parameters, an improved variation of the adaptive moment estimation (AdamW) algorithm is employed as the learning algorithm for the DFDNM because of its strong optimization ability. The experimental results and statistical analysis conducted across three Japanese prefectures confirm the efficacy and feasibility of the DFDNM while outperforming various state-of-the-art machine learning models. To the best of our knowledge, the proposed DFDNM is the first to restructure the dendritic neuron model's neural architecture, demonstrating promising use in multivariate time series prediction. Because of its optimal performance, the DFDNM may serve as an important reference for national and regional government decision-makers aiming to optimize pandemic prevention and medical resource management. We also verify that DFDMN is efficiently applicable not only to COVID-19 transmission prediction, but also to more general multivariate prediction tasks. It leads us to believe that it might be applied as a promising prediction model in other fields.
Collapse
Affiliation(s)
- Cheng Tang
- Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka, 819-0395, Japan; Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya-shi, 466-8555, Japan.
| | - Yuki Todo
- Faculty of Electrical and Computer Engineering, Kanazawa University, Kanazawa-shi, 920-1192, Japan
| | - Sachiko Kodera
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya-shi, 466-8555, Japan
| | - Rong Sun
- Faculty of Electrical and Computer Engineering, Kanazawa University, Kanazawa-shi, 920-1192, Japan; Division of Medical Oncology & Respiratory Medicine, Department of Internal Medicine, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Atsushi Shimada
- Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya-shi, 466-8555, Japan.
| |
Collapse
|
4
|
Pinto MF, Sirina J, Holliday ND, McWhirter CL. High-throughput kinetics in drug discovery. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2024; 29:100170. [PMID: 38964171 DOI: 10.1016/j.slasd.2024.100170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/21/2024] [Accepted: 06/17/2024] [Indexed: 07/06/2024]
Abstract
The importance of a drug's kinetic profile and interplay of structure-kinetic activity with PK/PD has long been appreciated in drug discovery. However, technical challenges have often limited detailed kinetic characterization of compounds to the latter stages of projects. This review highlights the advances that have been made in recent years in techniques, instrumentation, and data analysis to increase the throughput of detailed kinetic and mechanistic characterization, enabling its application earlier in the drug discovery process.
Collapse
Affiliation(s)
- Maria Filipa Pinto
- Artios Pharma Ltd, B940, Babraham Research Campus, Cambridge CB22 3FH, United Kingdom
| | - Julija Sirina
- Excellerate Bioscience Ltd, 21 The Triangle, NG2 Business Park, Nottingham, NG2 1AE, United Kingdom
| | - Nicholas D Holliday
- Excellerate Bioscience Ltd, 21 The Triangle, NG2 Business Park, Nottingham, NG2 1AE, United Kingdom; School of Life Sciences, The Medical School, University of Nottingham, Nottingham, NG7 2UH, United Kingdom
| | - Claire L McWhirter
- Artios Pharma Ltd, B940, Babraham Research Campus, Cambridge CB22 3FH, United Kingdom.
| |
Collapse
|
5
|
Keppler J. Laying the foundations for a theory of consciousness: the significance of critical brain dynamics for the formation of conscious states. Front Hum Neurosci 2024; 18:1379191. [PMID: 38736531 PMCID: PMC11082359 DOI: 10.3389/fnhum.2024.1379191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 04/15/2024] [Indexed: 05/14/2024] Open
Abstract
Empirical evidence indicates that conscious states, distinguished by the presence of phenomenal qualities, are closely linked to synchronized neural activity patterns whose dynamical characteristics can be attributed to self-organized criticality and phase transitions. These findings imply that insight into the mechanism by which the brain controls phase transitions will provide a deeper understanding of the fundamental mechanism by which the brain manages to transcend the threshold of consciousness. This article aims to show that the initiation of phase transitions and the formation of synchronized activity patterns is due to the coupling of the brain to the zero-point field (ZPF), which plays a central role in quantum electrodynamics (QED). The ZPF stands for the presence of ubiquitous vacuum fluctuations of the electromagnetic field, represented by a spectrum of normal modes. With reference to QED-based model calculations, the details of the coupling mechanism are revealed, suggesting that critical brain dynamics is governed by the resonant interaction of the ZPF with the most abundant neurotransmitter glutamate. The pyramidal neurons in the cortical microcolumns turn out to be ideally suited to control this interaction. A direct consequence of resonant glutamate-ZPF coupling is the amplification of specific ZPF modes, which leads us to conclude that the ZPF is the key to the understanding of consciousness and that the distinctive feature of neurophysiological processes associated with conscious experience consists in modulating the ZPF. Postulating that the ZPF is an inherently sentient field and assuming that the spectrum of phenomenal qualities is represented by the normal modes of the ZPF, the significance of resonant glutamate-ZPF interaction for the formation of conscious states becomes apparent in that the amplification of specific ZPF modes is inextricably linked with the excitation of specific phenomenal qualities. This theory of consciousness, according to which phenomenal states arise through resonant amplification of zero-point modes, is given the acronym TRAZE. An experimental setup is specified that can be used to test a corollary of the theory, namely, the prediction that normally occurring conscious perceptions are absent under experimental conditions in which resonant glutamate-ZPF coupling is disrupted.
Collapse
|
6
|
Ma P, Chen P, Tilden EI, Aggarwal S, Oldenborg A, Chen Y. Fast and slow: Recording neuromodulator dynamics across both transient and chronic time scales. SCIENCE ADVANCES 2024; 10:eadi0643. [PMID: 38381826 PMCID: PMC10881037 DOI: 10.1126/sciadv.adi0643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 01/17/2024] [Indexed: 02/23/2024]
Abstract
Neuromodulators transform animal behaviors. Recent research has demonstrated the importance of both sustained and transient change in neuromodulators, likely due to tonic and phasic neuromodulator release. However, no method could simultaneously record both types of dynamics. Fluorescence lifetime of optical reporters could offer a solution because it allows high temporal resolution and is impervious to sensor expression differences across chronic periods. Nevertheless, no fluorescence lifetime change across the entire classes of neuromodulator sensors was previously known. Unexpectedly, we find that several intensity-based neuromodulator sensors also exhibit fluorescence lifetime responses. Furthermore, we show that lifetime measures in vivo neuromodulator dynamics both with high temporal resolution and with consistency across animals and time. Thus, we report a method that can simultaneously measure neuromodulator change over transient and chronic time scales, promising to reveal the roles of multi-time scale neuromodulator dynamics in diseases, in response to therapies, and across development and aging.
Collapse
Affiliation(s)
- Pingchuan Ma
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
- Ph.D. Program in Neuroscience, Washington University, St. Louis, MO 63110, USA
| | - Peter Chen
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
- Master’s Program in Biomedical Engineering, Washington University, St. Louis, MO 63110, USA
| | - Elizabeth I. Tilden
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
- Ph.D. Program in Neuroscience, Washington University, St. Louis, MO 63110, USA
| | - Samarth Aggarwal
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
| | - Anna Oldenborg
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
| | - Yao Chen
- Department of Neuroscience, Washington University, St. Louis, MO 63110, USA
| |
Collapse
|
7
|
Nguyen QA, Klein PM, Xie C, Benthall KN, Iafrati J, Homidan J, Bendor JT, Dudok B, Farrell JS, Gschwind T, Porter CL, Keravala A, Dodson GS, Soltesz I. Acetylcholine receptor based chemogenetics engineered for neuronal inhibition and seizure control assessed in mice. Nat Commun 2024; 15:601. [PMID: 38238329 PMCID: PMC10796428 DOI: 10.1038/s41467-024-44853-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 01/09/2024] [Indexed: 01/22/2024] Open
Abstract
Epilepsy is a prevalent disorder involving neuronal network hyperexcitability, yet existing therapeutic strategies often fail to provide optimal patient outcomes. Chemogenetic approaches, where exogenous receptors are expressed in defined brain areas and specifically activated by selective agonists, are appealing methods to constrain overactive neuronal activity. We developed BARNI (Bradanicline- and Acetylcholine-activated Receptor for Neuronal Inhibition), an engineered channel comprised of the α7 nicotinic acetylcholine receptor ligand-binding domain coupled to an α1 glycine receptor anion pore domain. Here we demonstrate that BARNI activation by the clinical stage α7 nicotinic acetylcholine receptor-selective agonist bradanicline effectively suppressed targeted neuronal activity, and controlled both acute and chronic seizures in male mice. Our results provide evidence for the use of an inhibitory acetylcholine-based engineered channel activatable by both exogenous and endogenous agonists as a potential therapeutic approach to treating epilepsy.
Collapse
Affiliation(s)
- Quynh-Anh Nguyen
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA.
| | - Peter M Klein
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA.
| | - Cheng Xie
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Katelyn N Benthall
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Jillian Iafrati
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Jesslyn Homidan
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Jacob T Bendor
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Tilo Gschwind
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Charlotte L Porter
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Annahita Keravala
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - G Steven Dodson
- CODA Biotherapeutics, 240 East Grand Ave., South San Francisco, CA, 94080, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| |
Collapse
|
8
|
Orchard I, Lange AB. The neuroendocrine and endocrine systems in insect - Historical perspective and overview. Mol Cell Endocrinol 2024; 580:112108. [PMID: 37956790 DOI: 10.1016/j.mce.2023.112108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/02/2023] [Accepted: 11/07/2023] [Indexed: 11/15/2023]
Abstract
A complex cascade of events leads to the initiation and maintenance of a behavioral act in response to both internally and externally derived stimuli. These events are part of a transition of the animal into a new behavioral state, coordinated by chemicals that bias tissues and organs towards a new functional state of the animal. This form of integration is defined by the neuroendocrine (or neurosecretory) system and the endocrine system that release neurohormones or hormones, respectively. Here we describe the classical neuroendocrine and endocrine systems in insects to provide an historic perspective and overview of how neurohormones and hormones support plasticity in behavioral expression. Additionally, we describe peripheral tissues such as the midgut, epitracheal glands, and ovaries, which, whilst not necessarily being endocrine glands in the pure sense of the term, do produce and release hormones, thereby providing even more flexibility for inter-organ communication and regulation.
Collapse
Affiliation(s)
- Ian Orchard
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada.
| | - Angela B Lange
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada.
| |
Collapse
|
9
|
Rudibaugh TT, Stuppy SR, Keung AJ. Reactive Oxygen Species Mediate Transcriptional Responses to Dopamine and Cocaine in Human Cerebral Organoids. Int J Mol Sci 2023; 24:16474. [PMID: 38003664 PMCID: PMC10671319 DOI: 10.3390/ijms242216474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Dopamine signaling in the adult ventral forebrain regulates behavior, stress response, and memory formation and in neurodevelopment regulates neural differentiation and cell migration. Excessive dopamine levels, including those due to cocaine use in utero and in adults, could lead to long-term adverse consequences. The mechanisms underlying both homeostatic and pathological changes remain unclear, in part due to the diverse cellular responses elicited by dopamine and the reliance on animal models that exhibit species-specific differences in dopamine signaling. In this study, we use the human-derived ventral forebrain organoid model of Xiang-Tanaka and characterize their response to cocaine or dopamine. We explore dosing regimens of dopamine or cocaine to simulate acute or chronic exposure. We then use calcium imaging, cAMP imaging, and bulk RNA-sequencing to measure responses to cocaine or dopamine exposure. We observe an upregulation of inflammatory pathways in addition to indicators of oxidative stress following exposure. Using inhibitors of reactive oxygen species (ROS), we then show ROS to be necessary for multiple transcriptional responses of cocaine exposure. These results highlight novel response pathways and validate the potential of cerebral organoids as in vitro human models for studying complex biological processes in the brain.
Collapse
Affiliation(s)
| | | | - Albert J. Keung
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606, USA; (T.T.R.); (S.R.S.)
| |
Collapse
|
10
|
Henderson S, Strait M, Fernandes R, Xu H, Galligan JJ, Swain GM. Ex Vivo Electrochemical Monitoring of Cholinergic Signaling in the Mouse Colon Using an Enzyme-Based Biosensor. ACS Chem Neurosci 2023; 14:3460-3471. [PMID: 37681686 DOI: 10.1021/acschemneuro.3c00337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023] Open
Abstract
Cholinergic signaling, i.e., neurotransmission mediated by acetylcholine, is involved in a host of physiological processes, including learning and memory. Cholinergic dysfunction is commonly associated with neurodegenerative diseases, including Alzheimer's disease. In the gut, acetylcholine acts as an excitatory neuromuscular signaler to mediate smooth muscle contraction, which facilitates peristaltic propulsion. Gastrointestinal dysfunction has also been associated with Alzheimer's disease. This research focuses on the preparation of an electrochemical enzyme-based biosensor to monitor cholinergic signaling in the gut and its application for measuring electrically stimulated acetylcholine release in the mouse colon ex vivo. The biosensors were prepared by platinizing Pt microelectrodes through potential cycling in a potassium hexachloroplatinate (IV) solution to roughen the electrode surface and improve adhesion of the multienzyme film. These electrodes were then modified with a permselective poly(m-phenylenediamine) polymer film, which blocks electroactive interferents from reaching the underlying substrate while remaining permeable to small molecules like H2O2. A multienzyme film containing choline oxidase and acetylcholinesterase was then drop-cast on these modified electrodes. The sensor responds to acetylcholine and choline through the enzymatic production of H2O2, which is electrochemically oxidized to produce an increase in current with increasing acetylcholine or choline concentration. Important figures of merit include a sensitivity of 190 ± 10 mA mol-1 L cm-2, a limit of detection of 0.8 μmol L-1, and a batch reproducibility of 6.1% relative standard deviation at room temperature. These sensors were used to detect electrically stimulated acetylcholine release from mouse myenteric ganglia in the presence and absence of tetrodotoxin and neostigmine, an acetylcholinesterase inhibitor.
Collapse
Affiliation(s)
- Skye Henderson
- Department of Chemistry, Michigan State University, Ames, East Lansing, Michigan 48824, United States
| | - Madison Strait
- Department of Chemistry, Iowa State University, Ames, Iowa IA50011, United States
| | - Roxanne Fernandes
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Hui Xu
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, United States
| | - James J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Greg M Swain
- Department of Chemistry, Michigan State University, Ames, East Lansing, Michigan 48824, United States
| |
Collapse
|
11
|
Tzouvadaki I, Gkoupidenis P, Vassanelli S, Wang S, Prodromakis T. Interfacing Biology and Electronics with Memristive Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210035. [PMID: 36829290 DOI: 10.1002/adma.202210035] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Memristive technologies promise to have a large impact on modern electronics, particularly in the areas of reconfigurable computing and artificial intelligence (AI) hardware. Meanwhile, the evolution of memristive materials alongside the technological progress is opening application perspectives also in the biomedical field, particularly for implantable and lab-on-a-chip devices where advanced sensing technologies generate a large amount of data. Memristive devices are emerging as bioelectronic links merging biosensing with computation, acting as physical processors of analog signals or in the framework of advanced digital computing architectures. Recent developments in the processing of electrical neural signals, as well as on transduction and processing of chemical biomarkers of neural and endocrine functions, are reviewed. It is concluded with a critical perspective on the future applicability of memristive devices as pivotal building blocks in bio-AI fusion concepts and bionic schemes.
Collapse
Affiliation(s)
- Ioulia Tzouvadaki
- Centre for Microsystems Technology, Ghent University-IMEC, Ghent, 9052, Belgium
| | | | - Stefano Vassanelli
- NeuroChip Laboratory and Padova Neuroscience Centre, University of Padova, Padova, 35129, Italy
| | - Shiwei Wang
- Centre for Electronics Frontiers, The University of Edinburgh, Edinburgh, EH9 3JL, UK
| | - Themis Prodromakis
- Centre for Electronics Frontiers, The University of Edinburgh, Edinburgh, EH9 3JL, UK
| |
Collapse
|
12
|
Petroccione MA, D'Brant LY, Affinnih N, Wehrle PH, Todd GC, Zahid S, Chesbro HE, Tschang IL, Scimemi A. Neuronal glutamate transporters control reciprocal inhibition and gain modulation in D1 medium spiny neurons. eLife 2023; 12:e81830. [PMID: 37435808 PMCID: PMC10411972 DOI: 10.7554/elife.81830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 07/09/2023] [Indexed: 07/13/2023] Open
Abstract
Understanding the function of glutamate transporters has broad implications for explaining how neurons integrate information and relay it through complex neuronal circuits. Most of what is currently known about glutamate transporters, specifically their ability to maintain glutamate homeostasis and limit glutamate diffusion away from the synaptic cleft, is based on studies of glial glutamate transporters. By contrast, little is known about the functional implications of neuronal glutamate transporters. The neuronal glutamate transporter EAAC1 is widely expressed throughout the brain, particularly in the striatum, the primary input nucleus of the basal ganglia, a region implicated with movement execution and reward. Here, we show that EAAC1 limits synaptic excitation onto a population of striatal medium spiny neurons identified for their expression of D1 dopamine receptors (D1-MSNs). In these cells, EAAC1 also contributes to strengthen lateral inhibition from other D1-MSNs. Together, these effects contribute to reduce the gain of the input-output relationship and increase the offset at increasing levels of synaptic inhibition in D1-MSNs. By reducing the sensitivity and dynamic range of action potential firing in D1-MSNs, EAAC1 limits the propensity of mice to rapidly switch between behaviors associated with different reward probabilities. Together, these findings shed light on some important molecular and cellular mechanisms implicated with behavior flexibility in mice.
Collapse
Affiliation(s)
| | | | | | | | | | - Shergil Zahid
- SUNY Albany, Department of BiologyAlbanyUnited States
| | | | - Ian L Tschang
- SUNY Albany, Department of BiologyAlbanyUnited States
| | | |
Collapse
|
13
|
Rudibaugh TT, Keung AJ. Reactive Oxygen Species Mediate Transcriptional Responses to Dopamine and Cocaine in Human Cerebral Organoids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544782. [PMID: 37398046 PMCID: PMC10312668 DOI: 10.1101/2023.06.13.544782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Dopamine signaling in the adult ventral forebrain regulates behavior, stress response, and memory formation and in neurodevelopment regulates neural differentiation and cell migration. Excessive dopamine levels including due to cocaine use both in utero and in adults could lead to long-term adverse consequences. The mechanisms underlying both homeostatic and pathological changes remain unclear, partly due to the diverse cellular responses elicited by dopamine and the reliance on animal models that exhibit species-specific differences in dopamine signaling. To address these limitations, 3-D cerebral organoids have emerged as human-derived models, recapitulating salient features of human cell signaling and neurodevelopment. Organoids have demonstrated responsiveness to external stimuli, including substances of abuse, making them valuable investigative models. In this study we utilize the Xiang-Tanaka ventral forebrain organoid model and characterize their response to acute and chronic dopamine or cocaine exposure. The findings revealed a robust immune response, novel response pathways, and a potential critical role for reactive oxygen species (ROS) in the developing ventral forebrain. These results highlight the potential of cerebral organoids as in vitro human models for studying complex biological processes in the brain.
Collapse
Affiliation(s)
- Thomas T. Rudibaugh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606
| | - Albert J. Keung
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606
| |
Collapse
|
14
|
Chen J, Lin KC, Prasad S, Schmidtke DW. Label free impedance based acetylcholinesterase enzymatic biosensors for the detection of acetylcholine. Biosens Bioelectron 2023; 235:115340. [PMID: 37216844 DOI: 10.1016/j.bios.2023.115340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/08/2023] [Accepted: 04/18/2023] [Indexed: 05/24/2023]
Abstract
Realtime monitoring of neurotransmitters is of great interest for understanding their fundamental role in a wide range of biological processes in the central and peripheral nervous system, as well as their role, in several degenerative brain diseases. The measurement of acetylcholine in the brain is particularly challenging due to the complex environment of the brain and the low concentration and short lifetime of acetylcholine. In this paper, we demonstrated a novel, label-free biosensor for the detection of Ach using a single enzyme, acetylcholinesterase (ACHE), and electrochemical impedance spectroscopy (EIS). Acetylcholinesterase was covalently immobilized onto the surface of gold microelectrodes through an amine-reactive crosslinker dithiobis(succinimidyl propionate) (DSP). Passivation of the gold electrode with SuperBlock eliminated or reduced any non-specific response to other major interfering neurotransmitter molecules such as dopamine (DA), norepinephrine (NE) and epinephrine (EH). The sensors were able to detect acetylcholine over a wide concentration range (5.5-550 μM) in sample volumes as small as 300 μL by applying a 10 mV AC voltage at a frequency of 500 Hz. The sensors showed a linear relationship between Ach concentration and ΔZmod(R2 = 0.99) in PBS. The sensor responded to acetylcholine not only when evaluated in a simple buffer (PBS buffer) but in several more complex environments such as rat brain slurry and rat whole blood. The sensor remained responsive to acetylcholine after being implanted ex vivo in rat brain tissue. These results bode well for the future application of these novel sensors for real time in vivo monitoring of acetylcholine.
Collapse
Affiliation(s)
- Jie Chen
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75083, USA
| | - Kai-Chun Lin
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75083, USA
| | - Shalini Prasad
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75083, USA.
| | - David W Schmidtke
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75083, USA.
| |
Collapse
|
15
|
Cho W, Yoon SH, Chung TD. Streamlining the interface between electronics and neural systems for bidirectional electrochemical communication. Chem Sci 2023; 14:4463-4479. [PMID: 37152246 PMCID: PMC10155913 DOI: 10.1039/d3sc00338h] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 04/13/2023] [Indexed: 05/09/2023] Open
Abstract
Seamless neural interfaces conjoining neurons and electrochemical devices hold great potential for highly efficient signal transmission across neural systems and the external world. Signal transmission through chemical sensing and stimulation via electrochemistry is remarkable because communication occurs through the same chemical language of neurons. Emerging strategies based on synaptic interfaces, iontronics-based neuromodulation, and improvements in selective neurosensing techniques have been explored to achieve seamless integration and efficient neuro-electronics communication. Synaptic interfaces can directly exchange signals to and from neurons, in a similar manner to that of chemical synapses. Hydrogel-based iontronic chemical delivery devices are operationally compatible with neural systems for improved neuromodulation. In this perspective, we explore developments to improve the interface between neurons and electrodes by targeting neurons or sub-neuronal regions including synapses. Furthermore, recent progress in electrochemical neurosensing and iontronics-based chemical delivery is examined.
Collapse
Affiliation(s)
- Wonkyung Cho
- Department of Chemistry, Seoul National University Seoul 08826 Republic of Korea
| | - Sun-Heui Yoon
- Department of Chemistry, Seoul National University Seoul 08826 Republic of Korea
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University Seoul 08826 Republic of Korea
- Advanced Institutes of Convergence Technology Suwon-si 16229 Gyeonggi-do Republic of Korea
| |
Collapse
|
16
|
Kurkinen M, Fułek M, Fułek K, Beszłej JA, Kurpas D, Leszek J. The Amyloid Cascade Hypothesis in Alzheimer’s Disease: Should We Change Our Thinking? Biomolecules 2023; 13:biom13030453. [PMID: 36979388 PMCID: PMC10046826 DOI: 10.3390/biom13030453] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 02/15/2023] [Accepted: 02/18/2023] [Indexed: 03/05/2023] Open
Abstract
Old age increases the risk of Alzheimer’s disease (AD), the most common neurodegenerative disease, a devastating disorder of the human mind and the leading cause of dementia. Worldwide, 50 million people have the disease, and it is estimated that there will be 150 million by 2050. Today, healthcare for AD patients consumes 1% of the global economy. According to the amyloid cascade hypothesis, AD begins in the brain by accumulating and aggregating Aβ peptides and forming β-amyloid fibrils (Aβ42). However, in clinical trials, reducing Aβ peptide production and amyloid formation in the brain did not slow cognitive decline or improve daily life in AD patients. Prevention studies in cognitively unimpaired people at high risk or genetically destined to develop AD also have not slowed cognitive decline. These observations argue against the amyloid hypothesis of AD etiology, its development, and disease mechanisms. Here, we look at other avenues in the research of AD, such as the presenilin hypothesis, synaptic glutamate signaling, and the role of astrocytes and the glutamate transporter EAAT2 in the development of AD.
Collapse
Affiliation(s)
| | - Michał Fułek
- Department and Clinic of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology, Wroclaw Medical University, 50-556 Wroclaw, Poland
| | - Katarzyna Fułek
- Department and Clinic of Otolaryngology, Head and Neck Surgery, Wroclaw Medical University, 50-556 Wroclaw, Poland
- Correspondence: (K.F.); (J.L.)
| | | | - Donata Kurpas
- Department of Family Medicine, Wroclaw Medical University, 51-141 Wroclaw, Poland
| | - Jerzy Leszek
- Department and Clinic of Psychiatry, Wroclaw Medical University, 50-367 Wroclaw, Poland
- Correspondence: (K.F.); (J.L.)
| |
Collapse
|
17
|
Abstract
The genetically encoded fluorescent sensors convert chemical and physical signals into light. They are powerful tools for the visualisation of physiological processes in living cells and freely moving animals. The fluorescent protein is the reporter module of a genetically encoded biosensor. In this study, we first review the history of the fluorescent protein in full emission spectra on a structural basis. Then, we discuss the design of the genetically encoded biosensor. Finally, we briefly review several major types of genetically encoded biosensors that are currently widely used based on their design and molecular targets, which may be useful for the future design of fluorescent biosensors.
Collapse
Affiliation(s)
- Minji Wang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
| | - Yifan Da
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
| | - Yang Tian
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhong Shan Road North, Shanghai, 200062, China
| |
Collapse
|
18
|
Sudalaimani S, Arun S, Esokkiya A, Sanjeev Kumar K, Sivakumar C, Giribabu K. Disposable-micropipette tip supported electrified liquid-organogel interface as a platform for sensing acetylcholine. Analyst 2023; 148:1451-1459. [PMID: 36804568 DOI: 10.1039/d2an01663j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Sensing acetylcholine has been predominantly based on enzymatic strategies using acetylcholine esterase and choline oxidase because of its electrochemical inertness. Electrified liquid-liquid interfaces are not limited to oxidation/reduction processes, and can be utilized to detect non-redox molecules which cannot be detected using conventional solid electrodes. In this study, a disposable micropipette tip based liquid-organogel interface, in the presence/absence of calixarene has been developed as a platform for sensing acetylcholine. We also explored a liquid-liquid interface approach for sensing acetylcholine using a pre-pulled glass micropipette. In both approaches, the configuration, i.e., liquid-organogel and liquid-liquid interface-current linearly increases during the backward transfer of acetylcholine. The simple and facilitated ion transfer of acetylcholine across the liquid-organogel exhibited a linear range of 10-50 μM and 1-30 μM with a detection limit of 0.18 μM and 0.23 μM and a sensitivity of 9.52 nA μM-1 and 9.20 nA μM-1, respectively. Whereas, the detection limit of simple and facilitated ion transfer of liquid-liquid interface using pre-pulled glass micropipette was found to be 0.42 μM and 0.13 μM with a sensitivity of 5 × 10-3 nA μM-1 and 3.39 × 10-2 nA μM-1. The results indicate that the liquid-organogel configuration supported on a disposable micropipette tip without any pre-fabrication is highly suitable for electrified soft interface sensing applications.
Collapse
Affiliation(s)
- S Sudalaimani
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - S Arun
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India.
| | - A Esokkiya
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - K Sanjeev Kumar
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - C Sivakumar
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - K Giribabu
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi-630 003, Tamil Nadu, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| |
Collapse
|
19
|
Félix SS, Laurents DV, Oroz J, Cabrita EJ. Fused in sarcoma undergoes cold denaturation: Implications for phase separation. Protein Sci 2023; 32:e4521. [PMID: 36453011 PMCID: PMC9793971 DOI: 10.1002/pro.4521] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/04/2022]
Abstract
The mediation of liquid-liquid phase separation (LLPS) for fused in sarcoma (FUS) protein is generally attributed to the low-complexity, disordered domains and is enhanced at low temperature. The role of FUS folded domains on the LLPS process remains relatively unknown since most studies are mainly based on fragmented FUS domains. Here, we investigate the effect of metabolites on full-length (FL) FUS LLPS using turbidity assays and differential interference contrast (DIC) microscopy, and explore the behavior of the folded domains by nuclear magnetic resonance (NMR) spectroscopy. FL FUS LLPS is maximal at low concentrations of glucose and glutamate, moderate concentrations of NaCl, Zn2+ , and Ca2+ and at the isoelectric pH. The FUS RNA recognition motif (RRM) and zinc-finger (ZnF) domains are found to undergo cold denaturation above 0°C at a temperature that is determined by the conformational stability of the ZnF domain. Cold unfolding exposes buried nonpolar residues that can participate in LLPS-promoting hydrophobic interactions. Therefore, these findings constitute the first evidence that FUS globular domains may have an active role in LLPS under cold stress conditions and in the assembly of stress granules, providing further insight into the environmental regulation of LLPS.
Collapse
Affiliation(s)
- Sara S. Félix
- UCIBIO, Department of ChemistryNOVA School of Science and Technology, Universidade NOVA de LisboaCaparicaPortugal,Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de LisboaCaparicaPortugal,Instituto de Química Física Rocasolano (IQFR), CSICMadridSpain
| | | | - Javier Oroz
- Instituto de Química Física Rocasolano (IQFR), CSICMadridSpain
| | - Eurico J. Cabrita
- UCIBIO, Department of ChemistryNOVA School of Science and Technology, Universidade NOVA de LisboaCaparicaPortugal,Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de LisboaCaparicaPortugal
| |
Collapse
|
20
|
Juza R, Musilek K, Mezeiova E, Soukup O, Korabecny J. Recent advances in dopamine D 2 receptor ligands in the treatment of neuropsychiatric disorders. Med Res Rev 2023; 43:55-211. [PMID: 36111795 DOI: 10.1002/med.21923] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 07/29/2022] [Accepted: 08/09/2022] [Indexed: 02/04/2023]
Abstract
Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D2 Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D2 R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D2 R affinity. Four to six atoms chains are optimal for D2 R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D2 R affinity. In this review, we provide a thorough overview of the therapeutic potential of D2 R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D2 R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D2 R ligands and D2 R modulators from patents are not discussed in this review.
Collapse
Affiliation(s)
- Radomir Juza
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic
| | - Kamil Musilek
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Eva Mezeiova
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Ondrej Soukup
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Jan Korabecny
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| |
Collapse
|
21
|
Micro- and nano-devices for electrochemical sensing. Mikrochim Acta 2022; 189:459. [DOI: 10.1007/s00604-022-05548-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/02/2022] [Indexed: 11/24/2022]
Abstract
AbstractElectrode miniaturization has profoundly revolutionized the field of electrochemical sensing, opening up unprecedented opportunities for probing biological events with a high spatial and temporal resolution, integrating electrochemical systems with microfluidics, and designing arrays for multiplexed sensing. Several technological issues posed by the desire for downsizing have been addressed so far, leading to micrometric and nanometric sensing systems with different degrees of maturity. However, there is still an endless margin for researchers to improve current strategies and cope with demanding sensing fields, such as lab-on-a-chip devices and multi-array sensors, brain chemistry, and cell monitoring. In this review, we present current trends in the design of micro-/nano-electrochemical sensors and cutting-edge applications reported in the last 10 years. Micro- and nanosensors are divided into four categories depending on the transduction mechanism, e.g., amperometric, impedimetric, potentiometric, and transistor-based, to best guide the reader through the different detection strategies and highlight major advancements as well as still unaddressed demands in electrochemical sensing.
Graphical Abstract
Collapse
|
22
|
Dürst CD, Wiegert JS, Schulze C, Helassa N, Török K, Oertner TG. Vesicular release probability sets the strength of individual Schaffer collateral synapses. Nat Commun 2022; 13:6126. [PMID: 36253353 PMCID: PMC9576736 DOI: 10.1038/s41467-022-33565-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 09/22/2022] [Indexed: 12/24/2022] Open
Abstract
Information processing in the brain is controlled by quantal release of neurotransmitters, a tightly regulated process. From ultrastructural analysis, it is known that presynaptic boutons along single axons differ in the number of vesicles docked at the active zone. It is not clear whether the probability of these vesicles to get released (pves) is homogenous or also varies between individual boutons. Here, we optically measure evoked transmitter release at individual Schaffer collateral synapses at different calcium concentrations, using the genetically encoded glutamate sensor iGluSnFR. Fitting a binomial model to measured response amplitude distributions allowed us to extract the quantal parameters N, pves, and q. We find that Schaffer collateral boutons typically release single vesicles under low pves conditions and switch to multivesicular release in high calcium saline. The potency of individual boutons is highly correlated with their vesicular release probability while the number of releasable vesicles affects synaptic output only under high pves conditions.
Collapse
Affiliation(s)
- Céline D Dürst
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany
- Department of Basic Neurosciences, Center for Neurosciences (CMU), University of Geneva, 1211, Geneva, Switzerland
| | - J Simon Wiegert
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany
| | - Christian Schulze
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany
| | - Nordine Helassa
- Cell Biology and Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St George's, University of London, London, SW17 0RE, UK
- Department of Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - Katalin Török
- Cell Biology and Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St George's, University of London, London, SW17 0RE, UK
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany.
| |
Collapse
|
23
|
Li X, Hémond G, Godin AG, Doyon N. Computational modeling of trans-synaptic nanocolumns, a modulator of synaptic transmission. Front Comput Neurosci 2022; 16:969119. [PMID: 36249484 PMCID: PMC9554614 DOI: 10.3389/fncom.2022.969119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/01/2022] [Indexed: 12/01/2022] Open
Abstract
Understanding synaptic transmission is of crucial importance in neuroscience. The spatial organization of receptors, vesicle release properties and neurotransmitter molecule diffusion can strongly influence features of synaptic currents. Newly discovered structures coined trans-synaptic nanocolumns were shown to align presynaptic vesicles release sites and postsynaptic receptors. However, how these structures, spanning a few tens of nanometers, shape synaptic signaling remains little understood. Given the difficulty to probe submicroscopic structures experimentally, computer modeling is a useful approach to investigate the possible functional impacts and role of nanocolumns. In our in silico model, as has been experimentally observed, a nanocolumn is characterized by a tight distribution of postsynaptic receptors aligned with the presynaptic vesicle release site and by the presence of trans-synaptic molecules which can modulate neurotransmitter molecule diffusion. In this work, we found that nanocolumns can play an important role in reinforcing synaptic current mostly when the presynaptic vesicle contains a small number of neurotransmitter molecules. Our work proposes a new methodology to investigate in silico how the existence of trans-synaptic nanocolumns, the nanometric organization of the synapse and the lateral diffusion of receptors shape the features of the synaptic current such as its amplitude and kinetics.
Collapse
Affiliation(s)
- Xiaoting Li
- Department of Mathematics and Statistics, Université Laval, Québec City, QC, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Québec City, QC, Canada
- CERVO Brain Research Centre, Québec City, QC, Canada
| | - Gabriel Hémond
- Department of Physics, Université Laval, Québec City, QC, Canada
| | - Antoine G. Godin
- Department of Psychiatry and Neuroscience, Université Laval, Québec City, QC, Canada
- CERVO Brain Research Centre, Québec City, QC, Canada
- *Correspondence: Antoine G. Godin
| | - Nicolas Doyon
- Department of Mathematics and Statistics, Université Laval, Québec City, QC, Canada
- CERVO Brain Research Centre, Québec City, QC, Canada
- Nicolas Doyon
| |
Collapse
|
24
|
Wu CC, Huang SJ, Fu TY, Lin FL, Wang XY, Tan KT. Small-Molecule Modulated Affinity-Tunable Semisynthetic Protein Switches. ACS Sens 2022; 7:2691-2700. [PMID: 36084142 DOI: 10.1021/acssensors.2c01211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Engineered protein switches have been widely applied in cell-based protein sensors and point-of-care diagnosis for the rapid and simple analysis of a wide variety of proteins, metabolites, nucleic acids, and enzymatic activities. Currently, these protein switches are based on two main types of switching mechanisms to transduce the target binding event to a quantitative signal, through a change in the optical properties of fluorescent molecules and the activation of enzymatic activities. In this paper, we introduce a new affinity-tunable protein switch strategy in which the binding of a small-molecule target with the protein activates the streptavidin-biotin interaction to generate a readout signal. In the absence of a target, the biotinylated protein switch forms a closed conformation where the biotin is positioned in close proximity to the protein, imposing a large steric hindrance to prevent the effective binding with streptavidin. In the presence of the target molecule, this steric hindrance is removed, thereby exposing the biotin for streptavidin binding to produce strong fluorescent signals. With this modular sensing concept, various sulfonamide, methotrexate, and trimethoprim drugs can be selectively detected on the cell surface of native and genetically engineered cells using different fluorescent dyes and detection techniques.
Collapse
Affiliation(s)
- Chien-Chi Wu
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China
| | - Shao-Jie Huang
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China
| | - Tsung-Yu Fu
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China
| | - Fang-Ling Lin
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China
| | - Xin-You Wang
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China
| | - Kui-Thong Tan
- Department of Chemistry, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China.,Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101 Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan, Republic of China.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan, Republic of China
| |
Collapse
|
25
|
Gumnit MG, Watters JJ, Baker TL, Johnson SM, Johnson SM. Mu-opioid receptor-dependent transformation of respiratory motor pattern in neonates in vitro. Front Physiol 2022; 13:921466. [PMID: 35936900 PMCID: PMC9353126 DOI: 10.3389/fphys.2022.921466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/30/2022] [Indexed: 11/29/2022] Open
Abstract
Endogenous opioid peptides activating mu-opioid receptors (MORs) are part of an intricate neuromodulatory system that coordinates and optimizes respiratory motor output to maintain blood-gas homeostasis. MOR activation is typically associated with respiratory depression but also has excitatory effects on breathing and respiratory neurons. We hypothesized that low level MOR activation induces excitatory effects on the respiratory motor pattern. Thus, low concentrations of an MOR agonist drug (DAMGO, 10–200 nM) were bath-applied to neonatal rat brainstem-spinal cord preparations while recording inspiratory-related motor output on cervical spinal roots (C4-C5). Bath-applied DAMGO (50–200 nM) increased inspiratory motor burst amplitude by 40–60% during (and shortly following) drug application with decreased burst frequency and minute activity. Reciprocal changes in inspiratory burst amplitude and frequency were balanced such that 20 min after DAMGO (50–200 nM) application, minute activity was unaltered compared to pre-DAMGO levels. The DAMGO-induced inspiratory burst amplitude increase did not require crossed cervical spinal pathways, was expressed on thoracic ventral spinal roots (T4-T8) and remained unaltered by riluzole pretreatment (blocks persistent sodium currents associated with gasping). Split-bath experiments showed that the inspiratory burst amplitude increase was induced only when DAMGO was bath-applied to the brainstem and not the spinal cord. Thus, MOR activation in neonates induces a respiratory burst amplitude increase via brainstem-specific mechanisms. The burst amplitude increase counteracts the expected MOR-dependent frequency depression and may represent a new mechanism by which MOR activation influences respiratory motor output.
Collapse
|
26
|
Episodic Memory and Information Recognition Using Solitonic Neural Networks Based on Photorefractive Plasticity. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12115585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Neuromorphic models are proving capable of performing complex machine learning tasks, overcoming the structural limitations imposed by software algorithms and electronic architectures. Recently, both supervised and unsupervised learnings were obtained in photonic neurons by means of spatial-soliton-waveguide X-junctions. This paper investigates the behavior of networks based on these solitonic neurons, which are capable of performing complex tasks such as bit-to-bit information memorization and recognition. By exploiting photorefractive nonlinearity as if it were a biological neuroplasticity, the network modifies and adapts to the incoming signals, memorizing and recognizing them (photorefractive plasticity). The information processing and storage result in a plastic modification of the network interconnections. Theoretical description and numerical simulation of solitonic networks are reported and applied to the processing of 4-bit information.
Collapse
|
27
|
Tam RW, Keung AJ. Human Pluripotent Stem Cell-Derived Medium Spiny Neuron-like Cells Exhibit Gene Desensitization. Cells 2022; 11:cells11091411. [PMID: 35563715 PMCID: PMC9100557 DOI: 10.3390/cells11091411] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/17/2022] [Accepted: 04/20/2022] [Indexed: 02/04/2023] Open
Abstract
Gene desensitization in response to a repeated stimulus is a complex phenotype important across homeostatic and disease processes, including addiction, learning, and memory. These complex phenotypes are being characterized and connected to important physiologically relevant functions in rodent systems but are difficult to capture in human models where even acute responses to important neurotransmitters are understudied. Here through transcriptomic analysis, we map the dynamic responses of human stem cell-derived medium spiny neuron-like cells (hMSN-like cells) to dopamine. Furthermore, we show that these human neurons can reflect and capture cellular desensitization to chronic versus acute administration of dopamine. These human cells are further able to capture complex receptor crosstalk in response to the pharmacological perturbations of distinct dopamine receptor subtypes. This study demonstrates the potential utility and remaining challenges of using human stem cell-derived neurons to capture and study the complex dynamic mechanisms of the brain.
Collapse
|
28
|
Beltrán-Matas P, Castilho Á, Tencer B, Veruki ML, Hartveit E. Inhibitory inputs to an inhibitory interneuron: Spontaneous postsynaptic currents and GABA A receptors of A17 amacrine cells in the rat retina. Eur J Neurosci 2022; 55:1442-1470. [PMID: 35236011 PMCID: PMC9314042 DOI: 10.1111/ejn.15634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/29/2022]
Abstract
Amacrine cells constitute a large and heterogenous group of inhibitory interneurons in the retina. The A17 amacrine plays an important role for visual signaling in the rod pathway microcircuit of the mammalian retina. It receives excitatory input from rod bipolar cells and provides feedback inhibition to the same cells. However, from ultrastructural investigations, there is evidence for input to A17s from other types of amacrine cells, presumably inhibitory, but there is a lack of information about the identity and functional properties of the synaptic receptors and how inhibition contributes to the integrative properties of A17s. Here, we studied the biophysical and pharmacological properties of GABAergic spontaneous inhibitory postsynaptic currents (spIPSCs) and GABAA receptors of A17 amacrines, using whole-cell and outside-out patch recordings from rat retinal slices. The spIPSCs displayed fast onsets (10-90% rise time ~740 μs) and double-exponential decays (τfast ~4.5 ms [43% of amplitude]; τslow ~22 ms). Ultrafast application of brief pulses of GABA (3 mM) to patches evoked responses with deactivation kinetics best fitted by a triple-exponential function (τ1 ~5.3 ms [55% of amplitude]; τ2 ~48 ms [32% amplitude]; τ3 ~187 ms). Non-stationary noise analysis of spIPSCs and patch responses yielded single-channel conductances of ~21 and ~25 pS, respectively. Pharmacological analysis suggested that the spIPSCs are mediated by receptors with an α1βγ2 subunit composition and the somatic receptors have an α2βγ2 and/or α3βγ2 composition. These results demonstrate the presence of synaptic GABAA receptors on A17s, which may play an important role in signal integration in these cells.
Collapse
Affiliation(s)
| | - Áurea Castilho
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Barbora Tencer
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
| |
Collapse
|
29
|
Rapid Regulation of Glutamate Transport: Where Do We Go from Here? Neurochem Res 2022; 47:61-84. [PMID: 33893911 PMCID: PMC8542062 DOI: 10.1007/s11064-021-03329-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/08/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system (CNS). A family of five Na+-dependent transporters maintain low levels of extracellular glutamate and shape excitatory signaling. Shortly after the research group of the person being honored in this special issue (Dr. Baruch Kanner) cloned one of these transporters, his group and several others showed that their activity can be acutely (within minutes to hours) regulated. Since this time, several different signals and post-translational modifications have been implicated in the regulation of these transporters. In this review, we will provide a brief introduction to the distribution and function of this family of glutamate transporters. This will be followed by a discussion of the signals that rapidly control the activity and/or localization of these transporters, including protein kinase C, ubiquitination, glutamate transporter substrates, nitrosylation, and palmitoylation. We also include the results of our attempts to define the role of palmitoylation in the regulation of GLT-1 in crude synaptosomes. In some cases, the mechanisms have been fairly well-defined, but in others, the mechanisms are not understood. In several cases, contradictory phenomena have been observed by more than one group; we describe these studies with the goal of identifying the opportunities for advancing the field. Abnormal glutamatergic signaling has been implicated in a wide variety of psychiatric and neurologic disorders. Although recent studies have begun to link regulation of glutamate transporters to the pathogenesis of these disorders, it will be difficult to determine how regulation influences signaling or pathophysiology of glutamate without a better understanding of the mechanisms involved.
Collapse
|
30
|
Iwata T, Okumura Y, Okumura K, Horio T, Doi H, Takahashi K, Sawada K. Redox Sensor Array with 23.5-μm Resolution for Real-Time Imaging of Hydrogen Peroxide and Glutamate Based on Charge-Transfer-Type Potentiometric Sensor. SENSORS (BASEL, SWITZERLAND) 2021; 21:7682. [PMID: 34833757 PMCID: PMC8618362 DOI: 10.3390/s21227682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/11/2021] [Accepted: 11/15/2021] [Indexed: 11/17/2022]
Abstract
Towards clarifying the spatio-temporal neurotransmitter distribution, potentiometric redox sensor arrays with 23.5-µm resolution were fabricated. The sensor array based on a charge-transfer-type potentiometric sensor comprises 128×128 pixels with gold electrodes deposited on the surface of pixels. The sensor output corresponding to the interfacial potential of the electrode changed logarithmically with the mixture ratio of K3Fe(CN)6 and K4Fe(CN)6, where the redox sensitivity reached 49.9 mV/dec. By employing hydrogen peroxidase as an enzyme and ferrocene as an electron mediator, the sensing characteristics for hydrogen peroxide (H2O2) were investigated. The analyses of the sensing characteristics revealed that the sensitivity was about 44.7 mV/dec., comparable to the redox sensitivity, while the limit of detection (LOD) was achieved to be 1 µM. Furthermore, the oxidation state of the electron mediator can be the key to further lowering the LOD. Then, by immobilizing oxidizing enzyme for H2O2 and glutamate oxidase, glutamate (Glu) measurements were conducted. As a result, similar sensitivity and LOD to those of H2O2 were obtained. Finally, the real-time distribution of 1 µM Glu was visualized, demonstrating the feasibility of our device as a high-resolution bioimaging technique.
Collapse
Affiliation(s)
- Tatsuya Iwata
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
- Department of Electrical and Electronic Engineering, Toyama Prefectural University, Imizu 9390398, Japan
| | - Yuki Okumura
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| | - Koichi Okumura
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| | - Tomoko Horio
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| | - Hideo Doi
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| | - Kazuhiro Takahashi
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| | - Kazuaki Sawada
- Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi 4418580, Japan; (Y.O.); (K.O.); (T.H.); (H.D.); (K.T.); (K.S.)
| |
Collapse
|
31
|
Clay M, Monbouquette HG. Simulated Performance of Electroenzymatic Glutamate Biosensors In Vivo Illuminates the Complex Connection to Calibration In Vitro. ACS Chem Neurosci 2021; 12:4275-4285. [PMID: 34734695 DOI: 10.1021/acschemneuro.1c00365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Detailed simulations show that the relationship between electroenzymatic glutamate (Glut) sensor performance in vitro and that modeled in vivo is complicated by the influence of both resistances to mass transfer and clearance rates of Glut and H2O2 in the brain extracellular space (ECS). Mathematical modeling provides a powerful means to illustrate how these devices are expected to respond to a variety of conditions in vivo in ways that cannot be accomplished readily using existing experimental techniques. Through the use of transient model simulations in one spatial dimension, it is shown that the sensor response in vivo may exhibit much greater dependence on H2O2 mass transfer and clearance in the surrounding tissue than previously thought. This dependence may lead to sensor signals more than double the expected values (based on prior sensor calibration in vitro) for Glut release events within a few microns of the sensor surface. The sensor response in general is greatly affected by the distance between the device and location of Glut release, and apparent concentrations reported by simulated sensors consistently are well below the actual Glut levels for events occurring at distances greater than a few microns. Simulations of transient Glut concentrations, including a physiologically relevant bolus release, indicate that detection of Glut signaling likely is limited to events within 30 μm of the sensor surface based on representative sensor detection limits. It follows that important limitations also exist with respect to interpretation of decays in sensor signals, including relation of such data to actual Glut concentration declines in vivo. Thus, the use of sensor signal data to determine quantitatively the rates of Glut uptake from the brain ECS likely is problematic. The model is designed to represent a broad range of relevant physiological conditions, and although limited to one dimension, provides much needed guidance regarding the interpretation in general of electroenzymatic sensor data gathered in vivo.
Collapse
Affiliation(s)
- Mackenzie Clay
- Chemical and Biomolecular Engineering Department, University of California, Los Angeles, California 90095−1592, United States
| | - Harold G. Monbouquette
- Chemical and Biomolecular Engineering Department, University of California, Los Angeles, California 90095−1592, United States
| |
Collapse
|
32
|
Electrophysiology of ionotropic GABA receptors. Cell Mol Life Sci 2021; 78:5341-5370. [PMID: 34061215 PMCID: PMC8257536 DOI: 10.1007/s00018-021-03846-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 10/30/2022]
Abstract
GABAA receptors are ligand-gated chloride channels and ionotropic receptors of GABA, the main inhibitory neurotransmitter in vertebrates. In this review, we discuss the major and diverse roles GABAA receptors play in the regulation of neuronal communication and the functioning of the brain. GABAA receptors have complex electrophysiological properties that enable them to mediate different types of currents such as phasic and tonic inhibitory currents. Their activity is finely regulated by membrane voltage, phosphorylation and several ions. GABAA receptors are pentameric and are assembled from a diverse set of subunits. They are subdivided into numerous subtypes, which differ widely in expression patterns, distribution and electrical activity. Substantial variations in macroscopic neural behavior can emerge from minor differences in structure and molecular activity between subtypes. Therefore, the diversity of GABAA receptors widens the neuronal repertoire of responses to external signals and contributes to shaping the electrical activity of neurons and other cell types.
Collapse
|
33
|
Xia J, Yang H, Mu M, Micovic N, Poskanzer KE, Monaghan JR, Clark HA. Imaging in vivo acetylcholine release in the peripheral nervous system with a fluorescent nanosensor. Proc Natl Acad Sci U S A 2021; 118:e2023807118. [PMID: 33795516 PMCID: PMC8040656 DOI: 10.1073/pnas.2023807118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The ability to monitor the release of neurotransmitters during synaptic transmission would significantly impact the diagnosis and treatment of neurological diseases. Here, we present a DNA-based enzymatic nanosensor for quantitative detection of acetylcholine (ACh) in the peripheral nervous system of living mice. ACh nanosensors consist of DNA as a scaffold, acetylcholinesterase as a recognition component, pH-sensitive fluorophores as signal generators, and α-bungarotoxin as a targeting moiety. We demonstrate the utility of the nanosensors in the submandibular ganglia of living mice to sensitively detect ACh ranging from 0.228 to 358 μM. In addition, the sensor response upon electrical stimulation of the efferent nerve is dose dependent, reversible, and we observe a reduction of ∼76% in sensor signal upon pharmacological inhibition of ACh release. Equipped with an advanced imaging processing tool, we further spatially resolve ACh signal propagation on the tissue level. Our platform enables sensitive measurement and mapping of ACh transmission in the peripheral nervous system.
Collapse
Affiliation(s)
- Junfei Xia
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Hongrong Yang
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Michelle Mu
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Nicholas Micovic
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Kira E Poskanzer
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
- Kavli Insititute for Fundamental Neuroscience, San Francisco, CA 94143
| | - James R Monaghan
- Department of Biology, College of Science, Northeastern University, Boston, MA 02115
| | - Heather A Clark
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115;
- Department of Chemistry and Chemical Biology, College of Science, Northeastern University, Boston, MA 02115
| |
Collapse
|
34
|
Passlick S, Rose CR, Petzold GC, Henneberger C. Disruption of Glutamate Transport and Homeostasis by Acute Metabolic Stress. Front Cell Neurosci 2021; 15:637784. [PMID: 33603647 PMCID: PMC7884476 DOI: 10.3389/fncel.2021.637784] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/11/2021] [Indexed: 01/02/2023] Open
Abstract
High-affinity, Na+-dependent glutamate transporters are the primary means by which synaptically released glutamate is removed from the extracellular space. They restrict the spread of glutamate from the synaptic cleft into the perisynaptic space and reduce its spillover to neighboring synapses. Thereby, glutamate uptake increases the spatial precision of synaptic communication. Its dysfunction and the entailing rise of the extracellular glutamate concentration accompanied by an increased spread of glutamate result in a loss of precision and in enhanced excitation, which can eventually lead to neuronal death via excitotoxicity. Efficient glutamate uptake depends on a negative resting membrane potential as well as on the transmembrane gradients of the co-transported ions (Na+, K+, and H+) and thus on the proper functioning of the Na+/K+-ATPase. Consequently, numerous studies have documented the impact of an energy shortage, as occurring for instance during an ischemic stroke, on glutamate clearance and homeostasis. The observations range from rapid changes in the transport activity to altered expression of glutamate transporters. Notably, while astrocytes account for the majority of glutamate uptake under physiological conditions, they may also become a source of extracellular glutamate elevation during metabolic stress. However, the mechanisms of the latter phenomenon are still under debate. Here, we review the recent literature addressing changes of glutamate uptake and homeostasis triggered by acute metabolic stress, i.e., on a timescale of seconds to minutes.
Collapse
Affiliation(s)
- Stefan Passlick
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Division of Vascular Neurology, University Hospital Bonn, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, United Kingdom
| |
Collapse
|
35
|
Dijon NC, Nesheva DN, Holliday ND. Luciferase Complementation Approaches to Measure GPCR Signaling Kinetics and Bias. Methods Mol Biol 2021; 2268:249-274. [PMID: 34085274 DOI: 10.1007/978-1-0716-1221-7_17] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
An understanding of the kinetic contributions to G protein-coupled receptor pharmacology and signaling is increasingly important in compound profiling. Nonequilibrium conditions are commonly present in vivo, for example, as the drug competes with dynamic changes in hormone or neurotransmitter concentration for the receptor. Under such conditions individual binding kinetic properties of the ligands can influence duration of action, local ligand concentration, and functional properties such as the degree of insurmountable inhibition. Mapping the kinetic patterns of GPCR signaling events elicited by agonists, rather than a peak response at a single timepoint, is often key to predicting their functional impact. This is also a path to a better understanding of the origins of ligand bias, and whether such ligands demonstrate their effects through selection of distinct GPCR conformations, or via their kinetic properties. Recent developments in complementation approaches, based on a small bright shrimp luciferase Nanoluc, provide a new route to kinetic analysis of GPCR signaling in living cells that is amenable to the throughput required for compound profiling. In the NanoBiT luciferase complementation system, GPCRs and effector proteins are tagged with Nanoluc fragments optimized for their low interacting affinity and stability. The interactions brought about by GPCR recruitment of the effector are reproduced by a rapid and reversible increase in NanoBiT luminescence, in the presence of its substrate furimazine. Here we discuss the methods for optimizing and validating the GPCR NanoBiT assays, and protocols for their application to study endpoint and kinetic aspects of agonist and antagonist pharmacology. We also describe how timecourse families of agonist concentration response curves, derived from a single NanoBiT assay experiment, can be used to evaluate the kinetic components in operational model derived parameters of ligand bias.
Collapse
Affiliation(s)
- Nicola C Dijon
- School of Life Sciences, The Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK.,Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | - Desislava N Nesheva
- School of Life Sciences, The Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK.,Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK
| | - Nicholas D Holliday
- School of Life Sciences, The Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK. .,Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Nottingham, UK. .,Excellerate Bioscience, Biocity, Nottingham, UK.
| |
Collapse
|
36
|
Pierce SR, Germann AL, Evers AS, Steinbach JH, Akk G. Reduced Activation of the Synaptic-Type GABA A Receptor Following Prolonged Exposure to Low Concentrations of Agonists: Relationship between Tonic Activity and Desensitization. Mol Pharmacol 2020; 98:762-769. [PMID: 32978327 DOI: 10.1124/molpharm.120.000088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/09/2020] [Indexed: 01/16/2023] Open
Abstract
Synaptic GABAA receptors are alternately exposed to short pulses of a high, millimolar concentration of GABA and prolonged periods of low, micromolar concentration of the transmitter. Prior work has indicated that exposure to micromolar concentrations of GABA can both activate the postsynaptic receptors generating sustained low-amplitude current and desensitize the receptors, thereby reducing the peak amplitude of subsequent synaptic response. However, the precise relationship between tonic activation and reduction of peak response is not known. Here, we have measured the effect of prolonged exposure to GABA or the combination of GABA and the neurosteroid allopregnanolone, which was intended to desensitize a fraction of receptors, on a subsequent response to a high concentration of agonist in human α1β3γ2L receptors expressed in Xenopus oocytes. We show that the reduction in the peak amplitude of the post-exposure test response correlates with the open probability of the preceding desensitizing response. Curve fitting of the inhibitory relationship yielded an IC50 of 12.5 µM and a Hill coefficient of -1.61. The activation and desensitization data were mechanistically analyzed in the framework of a three-state Resting-Active-Desensitized model. Using the estimated affinity, efficacy, and desensitization parameters, we calculated the amount of desensitization that would accumulate during a long (2-minute) application of GABA or GABA plus allopregnanolone. The results indicate that accumulation of desensitization depends on the level of activity rather than agonist or potentiator concentration per se. We estimate that in the presence of 1 µM GABA, approximately 5% of α1β3γ2L receptors are functionally eliminated because of desensitization. SIGNIFICANCE STATEMENT: We present an analytical approach to quantify and predict the loss of activatable GABAA receptors due to desensitization in the presence of transmitter and the steroid allopregnanolone. The findings indicate that the peak amplitude of the synaptic response is influenced by ambient GABA and that changes in ambient concentrations of the transmitter and other GABAergic agents can modify tonically and phasically activated synaptic receptors in opposite directions.
Collapse
Affiliation(s)
- Spencer R Pierce
- Department of Anesthesiology (S.R.P., A.L.G., A.S.E., J.H.S., G.A.) and the Taylor Family Institute for Innovative Psychiatric Research (A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Allison L Germann
- Department of Anesthesiology (S.R.P., A.L.G., A.S.E., J.H.S., G.A.) and the Taylor Family Institute for Innovative Psychiatric Research (A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Alex S Evers
- Department of Anesthesiology (S.R.P., A.L.G., A.S.E., J.H.S., G.A.) and the Taylor Family Institute for Innovative Psychiatric Research (A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Joe Henry Steinbach
- Department of Anesthesiology (S.R.P., A.L.G., A.S.E., J.H.S., G.A.) and the Taylor Family Institute for Innovative Psychiatric Research (A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Department of Anesthesiology (S.R.P., A.L.G., A.S.E., J.H.S., G.A.) and the Taylor Family Institute for Innovative Psychiatric Research (A.S.E., J.H.S., G.A.), Washington University School of Medicine, St. Louis, Missouri
| |
Collapse
|
37
|
Birkner K, Wasser B, Ruck T, Thalman C, Luchtman D, Pape K, Schmaul S, Bitar L, Krämer-Albers EM, Stroh A, Meuth SG, Zipp F, Bittner S. β1-Integrin- and KV1.3 channel-dependent signaling stimulates glutamate release from Th17 cells. J Clin Invest 2020; 130:715-732. [PMID: 31661467 DOI: 10.1172/jci126381] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
Although the impact of Th17 cells on autoimmunity is undisputable, their pathogenic effector mechanism is still enigmatic. We discovered soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) complex proteins in Th17 cells that enable a vesicular glutamate release pathway that induces local intracytoplasmic calcium release and subsequent damage in neurons. This pathway is glutamine dependent and triggered by binding of β1-integrin to vascular cell adhesion molecule 1 (VCAM-1) on neurons in the inflammatory context. Glutamate secretion could be blocked by inhibiting either glutaminase or KV1.3 channels, which are known to be linked to integrin expression and highly expressed on stimulated T cells. Although KV1.3 is not expressed in CNS tissue, intrathecal administration of a KV1.3 channel blocker or a glutaminase inhibitor ameliorated disability in experimental neuroinflammation. In humans, T cells from patients with multiple sclerosis secreted higher levels of glutamate, and cerebrospinal fluid glutamine levels were increased. Altogether, our findings demonstrate that β1-integrin- and KV1.3 channel-dependent signaling stimulates glutamate release from Th17 cells upon direct cell-cell contact between Th17 cells and neurons.
Collapse
Affiliation(s)
- Katharina Birkner
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Beatrice Wasser
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Tobias Ruck
- Department of Neurology, University of Muenster, Muenster, Germany
| | - Carine Thalman
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Dirk Luchtman
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Katrin Pape
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Samantha Schmaul
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Lynn Bitar
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - Albrecht Stroh
- Institute for Pathophysiology, FTN, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Sven G Meuth
- Department of Neurology, University of Muenster, Muenster, Germany
| | - Frauke Zipp
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Stefan Bittner
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine Main Neuroscience Network (rmn2, ), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| |
Collapse
|
38
|
Doughty PT, Hossain I, Gong C, Ponder KA, Pati S, Arumugam PU, Murray TA. Novel microwire-based biosensor probe for simultaneous real-time measurement of glutamate and GABA dynamics in vitro and in vivo. Sci Rep 2020; 10:12777. [PMID: 32728074 PMCID: PMC7392771 DOI: 10.1038/s41598-020-69636-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022] Open
Abstract
Glutamate (GLU) and γ-aminobutyric acid (GABA) are the major excitatory (E) and inhibitory (I) neurotransmitters in the brain, respectively. Dysregulation of the E/I ratio is associated with numerous neurological disorders. Enzyme-based microelectrode array biosensors present the potential for improved biocompatibility, localized sample volumes, and much faster sampling rates over existing measurement methods. However, enzymes degrade over time. To overcome the time limitation of permanently implanted microbiosensors, we created a microwire-based biosensor that can be periodically inserted into a permanently implanted cannula. Biosensor coatings were based on our previously developed GLU and reagent-free GABA shank-type biosensor. In addition, the microwire biosensors were in the same geometric plane for the improved acquisition of signals in planar tissue including rodent brain slices, cultured cells, and brain regions with laminar structure. We measured real-time dynamics of GLU and GABA in rat hippocampal slices and observed a significant, nonlinear shift in the E/I ratio from excitatory to inhibitory dominance as electrical stimulation frequency increased from 10 to 140 Hz, suggesting that GABA release is a component of a homeostatic mechanism in the hippocampus to prevent excitotoxic damage. Additionally, we recorded from a freely moving rat over fourteen weeks, inserting fresh biosensors each time, thus demonstrating that the microwire biosensor overcomes the time limitation of permanently implanted biosensors and that the biosensors detect relevant changes in GLU and GABA levels that are consistent with various behaviors.
Collapse
Affiliation(s)
- P Timothy Doughty
- Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University, Ruston, LA, USA
| | - Imran Hossain
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA
| | - Chenggong Gong
- Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA
| | - Kayla A Ponder
- Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University, Ruston, LA, USA
| | - Sandipan Pati
- UAB Epilepsy Center/Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Prabhu U Arumugam
- Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University, Ruston, LA, USA. .,Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA.
| | - Teresa A Murray
- Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University, Ruston, LA, USA.
| |
Collapse
|
39
|
Meyrath M, Szpakowska M, Zeiner J, Massotte L, Merz MP, Benkel T, Simon K, Ohnmacht J, Turner JD, Krüger R, Seutin V, Ollert M, Kostenis E, Chevigné A. The atypical chemokine receptor ACKR3/CXCR7 is a broad-spectrum scavenger for opioid peptides. Nat Commun 2020; 11:3033. [PMID: 32561830 PMCID: PMC7305236 DOI: 10.1038/s41467-020-16664-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 05/15/2020] [Indexed: 12/29/2022] Open
Abstract
Endogenous opioid peptides and prescription opioid drugs modulate pain, anxiety and stress by activating opioid receptors, currently classified into four subtypes. Here we demonstrate that ACKR3/CXCR7, hitherto known as an atypical scavenger receptor for chemokines, is a broad-spectrum scavenger of opioid peptides. Phylogenetically, ACKR3 is intermediate between chemokine and opioid receptors and is present in various brain regions together with classical opioid receptors. Functionally, ACKR3 is a scavenger receptor for a wide variety of opioid peptides, especially enkephalins and dynorphins, reducing their availability for the classical opioid receptors. ACKR3 is not modulated by prescription opioids, but we show that an ACKR3-selective subnanomolar competitor peptide, LIH383, can restrain ACKR3’s negative regulatory function on opioid peptides in rat brain and potentiate their activity towards classical receptors, which may open alternative therapeutic avenues for opioid-related disorders. Altogether, our results reveal that ACKR3 is an atypical opioid receptor with cross-family ligand selectivity. Opioids modulate pain, anxiety and stress by activating four subtypes of opioid receptors. The authors show that atypical chemokine receptor 3 (ACKR3) is a scavenger for various endogenous opioid peptides regulating their availability without activating downstream signaling.
Collapse
Affiliation(s)
- Max Meyrath
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg
| | - Martyna Szpakowska
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg
| | - Julian Zeiner
- Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115, Bonn, Germany
| | - Laurent Massotte
- Neurophysiology Unit, GIGA Neurosciences, University of Liège, avenue de l'hopital, B-4000, Liège, Belgium
| | - Myriam P Merz
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg
| | - Tobias Benkel
- Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115, Bonn, Germany.,Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Katharina Simon
- Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115, Bonn, Germany
| | - Jochen Ohnmacht
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, avenue du Swing 6, L-4367, Belvaux, Luxembourg.,Department of Life Sciences and Medicine, University of Luxembourg, avenue du Swing 6, L-4367, Belvaux, Luxembourg
| | - Jonathan D Turner
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg
| | - Rejko Krüger
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, avenue du Swing 6, L-4367, Belvaux, Luxembourg.,Transversal Translational Medicine, Luxembourg Institute of Health (LIH), rue Thomas Edison 1A-B, L-1445, Strassen, Luxembourg
| | - Vincent Seutin
- Neurophysiology Unit, GIGA Neurosciences, University of Liège, avenue de l'hopital, B-4000, Liège, Belgium
| | - Markus Ollert
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg.,Department of Dermatology and Allergy Center, Odense Research Center for Anaphylaxis, University of Southern Denmark, 5000, Odense, Denmark
| | - Evi Kostenis
- Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115, Bonn, Germany
| | - Andy Chevigné
- Department of Infection and Immunity, Luxembourg Institute of Health (LIH), rue Henri Koch 29, L-4354, Esch-sur-Alzette, Luxembourg.
| |
Collapse
|
40
|
Matt SM, Gaskill PJ. Where Is Dopamine and how do Immune Cells See it?: Dopamine-Mediated Immune Cell Function in Health and Disease. J Neuroimmune Pharmacol 2020; 15:114-164. [PMID: 31077015 PMCID: PMC6842680 DOI: 10.1007/s11481-019-09851-4] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/07/2019] [Indexed: 02/07/2023]
Abstract
Dopamine is well recognized as a neurotransmitter in the brain, and regulates critical functions in a variety of peripheral systems. Growing research has also shown that dopamine acts as an important regulator of immune function. Many immune cells express dopamine receptors and other dopamine related proteins, enabling them to actively respond to dopamine and suggesting that dopaminergic immunoregulation is an important part of proper immune function. A detailed understanding of the physiological concentrations of dopamine in specific regions of the human body, particularly in peripheral systems, is critical to the development of hypotheses and experiments examining the effects of physiologically relevant dopamine concentrations on immune cells. Unfortunately, the dopamine concentrations to which these immune cells would be exposed in different anatomical regions are not clear. To address this issue, this comprehensive review details the current information regarding concentrations of dopamine found in both the central nervous system and in many regions of the periphery. In addition, we discuss the immune cells present in each region, and how these could interact with dopamine in each compartment described. Finally, the review briefly addresses how changes in these dopamine concentrations could influence immune cell dysfunction in several disease states including Parkinson's disease, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, as well as the collection of pathologies, cognitive and motor symptoms associated with HIV infection in the central nervous system, known as NeuroHIV. These data will improve our understanding of the interactions between the dopaminergic and immune systems during both homeostatic function and in disease, clarify the effects of existing dopaminergic drugs and promote the creation of new therapeutic strategies based on manipulating immune function through dopaminergic signaling. Graphical Abstract.
Collapse
Affiliation(s)
- S M Matt
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - P J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA.
| |
Collapse
|
41
|
Liao R, Wood TR, Nance E. Superoxide dismutase reduces monosodium glutamate-induced injury in an organotypic whole hemisphere brain slice model of excitotoxicity. J Biol Eng 2020; 14:3. [PMID: 32042309 PMCID: PMC7001228 DOI: 10.1186/s13036-020-0226-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/29/2020] [Indexed: 12/26/2022] Open
Abstract
Background Knowledge of glutamate excitotoxicity has increased substantially over the past few decades, with multiple proposed pathways involved in inflicting damage. We sought to develop a monosodium glutamate (MSG) exposed ex vivo organotypic whole hemisphere (OWH) brain slice model of excitotoxicity to study excitotoxic processes and screen the efficacy of superoxide dismutase (SOD). Results The OWH model is a reproducible platform with high cell viability and retained cellular morphology. OWH slices exposed to MSG induced significant cytotoxicity and downregulation of neuronal excitation-related gene expression. The OWH brain slice model has enabled us to isolate and study components of excitotoxicity, distinguishing the effects of glutamate excitation, hyperosmolar stress, and inflammation. We find that extracellularly administered SOD is significantly protective in inhibiting cell death and restoring healthy mitochondrial morphology. SOD efficacy suggests that superoxide scavenging is a promising therapeutic strategy in excitotoxic injury. Conclusions Using OWH brain slice models, we can obtain a better understanding of the pathological mechanisms of excitotoxic injury, and more rapidly screen potential therapeutics.
Collapse
Affiliation(s)
- Rick Liao
- 1Department of Chemical Engineering, University of Washington, 3781 Okanogan Lane NE, Seattle, WA 98195 USA
| | - Thomas R Wood
- 2Department of Pediatrics, University of Washington, Seattle, WA USA
| | - Elizabeth Nance
- 1Department of Chemical Engineering, University of Washington, 3781 Okanogan Lane NE, Seattle, WA 98195 USA.,3Department of Radiology, University of Washington, Seattle, WA USA.,4Center on Human Development and Disability, University of Washington, Seattle, WA USA
| |
Collapse
|
42
|
Josey BP, Heinrich F, Silin V, Lösche M. Association of Model Neurotransmitters with Lipid Bilayer Membranes. Biophys J 2020; 118:1044-1057. [PMID: 32032504 DOI: 10.1016/j.bpj.2020.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 11/15/2022] Open
Abstract
Aimed at reproducing the results of electrophysiological studies of synaptic signal transduction, conventional models of neurotransmission are based on the specific binding of neurotransmitters to ligand-gated receptor ion channels. However, the complex kinetic behavior observed in synaptic transmission cannot be reproduced in a standard kinetic model without the ad hoc postulation of additional conformational channel states. On the other hand, if one invokes unspecific neurotransmitter adsorption to the bilayer-a process not considered in the established models-the electrophysiological data can be rationalized with only the standard set of three conformational receptor states that also depend on this indirect coupling of neurotransmitters via their membrane interaction. Experimental verification has been difficult because binding affinities of neurotransmitters to the lipid bilayer are low. We quantify this interaction with surface plasmon resonance to measure equilibrium dissociation constants in neurotransmitter membrane association. Neutron reflection measurements on artificial membranes, so-called sparsely tethered bilayer lipid membranes, reveal the structural aspects of neurotransmitters' association with zwitterionic and anionic bilayers. We thus establish that serotonin interacts nonspecifically with the membrane at physiologically relevant concentrations, whereas γ-aminobutyric acid does not. Surface plasmon resonance shows that serotonin adsorbs with millimolar affinity, and neutron reflectometry shows that it penetrates the membrane deeply, whereas γ-aminobutyric is excluded from the bilayer.
Collapse
Affiliation(s)
- Brian P Josey
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland
| | - Vitalii Silin
- Institute for Bioscience and Biotechnology Research, Rockville, Maryland
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.
| |
Collapse
|
43
|
Moody AS, Payne TD, Barth BA, Sharma B. Surface-enhanced spatially-offset Raman spectroscopy (SESORS) for detection of neurochemicals through the skull at physiologically relevant concentrations. Analyst 2020; 145:1885-1893. [DOI: 10.1039/c9an01708a] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Detection techniques for neurotransmitters that are rapid, label-free, and non-invasive are needed to move towards earlier diagnosis of neurological disease.
Collapse
Affiliation(s)
- Amber S. Moody
- Department of Chemistry
- University of Tennessee Knoxville
- Knoxville
- USA
| | - Taylor D. Payne
- Department of Chemistry
- University of Tennessee Knoxville
- Knoxville
- USA
| | - Brian A. Barth
- Department of Chemical Engineering
- University of Tennessee Knoxville
- Knoxville
- USA
| | - Bhavya Sharma
- Department of Chemistry
- University of Tennessee Knoxville
- Knoxville
- USA
| |
Collapse
|
44
|
Coates C, Kerruth S, Helassa N, Török K. Kinetic Mechanisms of Fast Glutamate Sensing by Fluorescent Protein Probes. Biophys J 2019; 118:117-127. [PMID: 31787209 DOI: 10.1016/j.bpj.2019.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 11/01/2019] [Accepted: 11/11/2019] [Indexed: 01/18/2023] Open
Abstract
We have developed probes based on the bacterial periplasmic glutamate/aspartate binding protein with either an endogenously fluorescent protein or a synthetic fluorophore as the indicator of glutamate binding for studying the kinetic mechanism of glutamate binding. iGluSnFR variants termed iGluh, iGlum, and iGlul cover a broad range of Kd-s (5.8 μM and 2.1 and 50 mM, respectively), and a novel fluorescently labeled indicator, Fl-GluBP, has a Kd of 9.7 μM. The fluorescence response kinetics of all the probes are consistent with a two-step mechanism involving ligand binding and isomerization either of the apo or the ligand-bound binding protein. Although the previously characterized ultrafast indicators iGluu and iGluf had monophasic fluorescence enhancement that occurred in the rate limiting isomerization step, the sensors described here all have biphasic binding kinetics with fluorescence increases occurring both in the glutamate binding and the isomerization steps. For iGlum and iGlul, the data indicate prebinding conformational change followed by ligand binding. In contrast, for iGluh and Fl-GluBP, glutamate binding is followed by isomerization. Thus, the effects of structural heterogeneity introduced by single amino acid changes around the binding site on the kinetic path of interactions with glutamate are revealed. Remarkably, glutamate binding with a diffusion-limited rate constant to iGluh and Fl-GluBP is detected for the first time, hinting at the underlying mechanism of the supremely rapid activation of the highly homologous α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor by glutamate binding.
Collapse
Affiliation(s)
- Catherine Coates
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Silke Kerruth
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Nordine Helassa
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom
| | - Katalin Török
- Molecular and Clinical Sciences Research Institute, St. George's University of London, London, United Kingdom.
| |
Collapse
|
45
|
Atkinson-Dell R, Mohamet L. Induced Pluripotent Stem Cell-Derived Astroglia: A New Tool for Research Towards the Treatment of Alzheimer's Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:383-405. [PMID: 31583596 DOI: 10.1007/978-981-13-9913-8_15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite over a century of research into Alzheimer's disease (AD), progress in understanding the complex aetiology has been hindered, in part, by a lack of human, disease relevant, cellular models, reflected in an inability to translate results from animal studies to successful human therapies. Induced pluripotent stem cell (iPSC) technology, in which somatic cells are reprogrammed to pluripotent stem cells, creates an ideal physiologically relevant model as they maintain the genetic identity of the donor. These iPSCs can self-renew indefinitely in vitro and have the capacity to differentiate into any cell type, opening up new discovery and therapeutic opportunities. Despite a plethora of publications indicating the generation and utility of iPSC-derived neurones for disease modelling to date, in comparison only a limited number of studies have described generation of enriched astroglia from patients with early- or late-stage onset of AD. We recently reported that iPSC-astroglia derived from these patients are capable of mimicking a wide variety of deficits in homeostatic molecular cascades, intimately associated with AD, that are routinely observed in vivo. This review examines the opportunities and limitations of this innovative technology in the context of AD modelling and uses for preclinical discovery to improve our success for an efficacious therapeutic outcome.
Collapse
Affiliation(s)
| | - Lisa Mohamet
- StrataStem Ltd., Suite 112, 4a Rylands Street, Warrington, WA1 1EN, UK.
| |
Collapse
|
46
|
Germann AL, Pierce SR, Senneff TC, Burbridge AB, Steinbach JH, Akk G. Steady-state activation and modulation of the synaptic-type α1β2γ2L GABA A receptor by combinations of physiological and clinical ligands. Physiol Rep 2019; 7:e14230. [PMID: 31549483 PMCID: PMC6757177 DOI: 10.14814/phy2.14230] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 11/24/2022] Open
Abstract
The synaptic α1β2γ2 GABAA receptor is activated phasically by presynaptically released GABA. The receptor is considered to be inactive between synaptic events when exposed to ambient GABA because of its low resting affinity to the transmitter. We tested the hypothesis that a combination of physiological and/or clinical positive allosteric modulators of the GABAA receptor with ambient GABA generates measurable steady-state activity. Recombinant α1β2γ2L GABAA receptors were expressed in Xenopus oocytes and activated by combinations of low concentrations of orthosteric (GABA, taurine) and allosteric (the steroid allopregnanolone, the anesthetic propofol) agonists, in the absence and presence of the inhibitory steroid pregnenolone sulfate. Steady-state activity was analyzed using the three-state cyclic Resting-Active-Desensitized model. We estimate that the steady-state open probability of the synaptic α1β2γ2L GABAA receptor in the presence of ambient GABA (1 μmol/L), taurine (10 μmol/L), and physiological levels of allopregnanolone (0.01 μmol/L) and pregnenolone sulfate (0.1 μmol/L) is 0.008. Coapplication of a clinical concentration of propofol (1 μmol/L) increases the steady-state open probability to 0.03. Comparison of total charge transfer for phasic and tonic activity indicates that steady-state activity can contribute strongly (~20 to >99%) to integrated activity from the synaptic GABAA receptor.
Collapse
Affiliation(s)
- Allison L. Germann
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
| | - Spencer R. Pierce
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
| | - Thomas C. Senneff
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
| | - Ariel B. Burbridge
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
| | - Joe Henry Steinbach
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
- Taylor Family Institute for Innovative Psychiatric ResearchWashington University School of MedicineSt. LouisMissouri
| | - Gustav Akk
- Department of AnesthesiologyWashington University School of MedicineSt. LouisMissouri
- Taylor Family Institute for Innovative Psychiatric ResearchWashington University School of MedicineSt. LouisMissouri
| |
Collapse
|
47
|
Conceição EPS, Madden CJ, Morrison SF. Neurons in the rat ventral lateral preoptic area are essential for the warm-evoked inhibition of brown adipose tissue and shivering thermogenesis. Acta Physiol (Oxf) 2019; 225:e13213. [PMID: 30365209 PMCID: PMC6686665 DOI: 10.1111/apha.13213] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/25/2018] [Accepted: 10/19/2018] [Indexed: 12/31/2022]
Abstract
AIM To determine the role of neurons in the ventral part of the lateral preoptic area (vLPO) in CNS thermoregulation. METHODS In vivo electrophysiological and neuropharmacological were used to evaluate the contribution of neurons in the vLPO to the regulation of brown adipose tissue (BAT) thermogenesis and muscle shivering in urethane/chloralose-anaesthetized rats. RESULTS Nanoinjections of NMDA targeting the medial preoptic area (MPA) and the vLPO suppressed the cold-evoked BAT sympathetic activity (SNA), reduced the BAT temperature (TBAT ), expired CO2 , mean arterial pressure (MAP), and heart rate. Inhibition of vLPO neurons with muscimol or AP5/CNQX elicited increases in BAT SNA, TBAT , tachycardia, and small elevations in MAP. The BAT thermogenesis evoked by AP5/CNQX in vLPO was inhibited by the activation of MPA neurons. The inhibition of BAT SNA by vLPO neurons does not require a GABAergic input to dorsomedial hypothalamus (DMH), but MPA provides a GABAergic input to DMH. The activation of vLPO neurons inhibits the BAT thermogenesis evoked by NMDA in the rostral raphe pallidus (rRPa), but not that after bicuculline in rRPa. The BAT thermogenesis elicited by vLPO inhibition is dependent on glutamatergic inputs to DMH and rRPa, but these excitatory inputs do not arise from MnPO neurons. The activation of neurons in the vLPO also inhibits cold- and prostaglandin-evoked muscle shivering, and vLPO inhibition is sufficient to evoke shivering. CONCLUSION The vLPO contains neurons that are required for the warm ambient-evoked inhibition of muscle shivering and of BAT thermogenesis, mediated through a direct or indirect GABAergic input to rRPa from vLPO.
Collapse
Affiliation(s)
- Ellen P S Conceição
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon
| | - Christopher J Madden
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon
| | - Shaun F Morrison
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon
| |
Collapse
|
48
|
Single Synapse Indicators of Impaired Glutamate Clearance Derived from Fast iGlu u Imaging of Cortical Afferents in the Striatum of Normal and Huntington (Q175) Mice. J Neurosci 2019; 39:3970-3982. [PMID: 30819797 DOI: 10.1523/jneurosci.2865-18.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/05/2019] [Accepted: 02/19/2019] [Indexed: 01/23/2023] Open
Abstract
Changes in the balance between glutamate (Glu) release and uptake may stimulate synaptic reorganization and even synapse loss. In the case of neurodegeneration, a mismatch between astroglial Glu uptake and presynaptic Glu release could be detected if both parameters were assessed independently and at a single-synapse level. This has now become possible due to a new imaging assay with the genetically encoded ultrafast Glu sensor iGlu u We report findings from individual corticostriatal synapses in acute slices prepared from mice of either sex that were >1 year of age. Contrasting patterns of short-term plasticity and a size criterion identified two classes of terminals, presumably corresponding to the previously defined IT (intratelencephalic) and PT (pyramidal tract) synapses. The latter exhibited a higher degree of frequency potentiation/residual Glu accumulation and were selected for our first iGlu u single-synapse study in Q175 mice, a model of Huntington's disease (HD). In HD mice, the decay time constant of the perisynaptic Glu concentration (TauD), as an indicator of uptake, and the peak iGlu u amplitude, as an indicator of release, were prolonged and reduced, respectively. Treatment of WT preparations with the astrocytic Glu uptake blocker TFB-TBOA (100 nm) mimicked the TauD changes in homozygotes. Considering the largest TauD values encountered in WT, ∼40% of PT synapses tested in Q175 heterozygotes can be classified as dysfunctional. Moreover, HD but not WT synapses exhibited a positive correlation between TauD and the peak amplitude of iGlu u Finally, EAAT2 (excitatory amino acid transport protein 2) immunoreactivity was reduced next to corticostriatal terminals. Thus, astrocytic Glu transport remains a promising target for therapeutic intervention.SIGNIFICANCE STATEMENT Alterations in astrocytic Glu uptake can play a role in synaptic plasticity and neurodegeneration. Until now, the sensitivity of synaptic responses to pharmacological transport block and the resulting activation of NMDA receptors were regarded as reliable evidence for a mismatch between synaptic uptake and release. But the latter parameters are interdependent. Using a new genetically encoded sensor to monitor extracellular glutamate concentration ([Glu]) at individual corticostriatal synapses, we can now quantify the time constant of perisynaptic [Glu] decay (as an indicator of uptake) and the maximal [Glu] elevation next to the active zone (as an indicator of Glu release). The results provide a positive answer to the hitherto unresolved question of whether neurodegeneration (e.g., Huntington's disease) associates with a glutamate uptake deficit at tripartite excitatory synapses.
Collapse
|
49
|
Advances in Engineering and Application of Optogenetic Indicators for Neuroscience. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9030562] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Our ability to investigate the brain is limited by available technologies that can record biological processes in vivo with suitable spatiotemporal resolution. Advances in optogenetics now enable optical recording and perturbation of central physiological processes within the intact brains of model organisms. By monitoring key signaling molecules noninvasively, we can better appreciate how information is processed and integrated within intact circuits. In this review, we describe recent efforts engineering genetically-encoded fluorescence indicators to monitor neuronal activity. We summarize recent advances of sensors for calcium, potassium, voltage, and select neurotransmitters, focusing on their molecular design, properties, and current limitations. We also highlight impressive applications of these sensors in neuroscience research. We adopt the view that advances in sensor engineering will yield enduring insights on systems neuroscience. Neuroscientists are eager to adopt suitable tools for imaging neural activity in vivo, making this a golden age for engineering optogenetic indicators.
Collapse
|
50
|
Waataja JJ, Peterson CD, Verma H, Goracke-Postle CJ, Séguéla P, Delpire E, Wilcox GL, Fairbanks CA. Agmatine preferentially antagonizes GluN2B-containing N-methyl-d-aspartate receptors in spinal cord. J Neurophysiol 2019; 121:662-671. [PMID: 30427758 PMCID: PMC6397392 DOI: 10.1152/jn.00172.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 11/12/2018] [Accepted: 11/14/2018] [Indexed: 12/28/2022] Open
Abstract
The role of the N-methyl-d-aspartate receptor (NMDAr) as a contributor to maladaptive neuroplasticity underlying the maintenance of chronic pain is well established. Agmatine, an NMDAr antagonist, has been shown to reverse tactile hypersensitivity in rodent models of neuropathic pain while lacking the side effects characteristic of global NMDAr antagonism, including sedation and motor impairment, indicating a likely subunit specificity of agmatine's NMDAr inhibition. The present study assessed whether agmatine inhibits subunit-specific NMDAr-mediated current in the dorsal horn of mouse spinal cord slices. We isolated NMDAr-mediated excitatory postsynaptic currents (EPSCs) in small lamina II dorsal horn neurons evoked by optogenetic stimulation of Nav1.8-containing nociceptive afferents. We determined that agmatine abbreviated the amplitude, duration, and decay constant of NMDAr-mediated EPSCs similarly to the application of the GluN2B antagonist ifenprodil. In addition, we developed a site-specific knockdown of the GluN2B subunit of the NMDAr. We assessed whether agmatine and ifenprodil were able to inhibit NMDAr-mediated current in the spinal cord dorsal horn of mice lacking the GluN2B subunit of the NMDAr by analysis of electrically evoked EPSCs. In control mouse spinal cord, agmatine and ifenprodil both inhibited amplitude and accelerated the decay kinetics. However, agmatine and ifenprodil failed to attenuate the decay kinetics of NMDAr-mediated EPSCs in the GluN2B-knockdown mouse spinal cord. The present study indicates that agmatine preferentially antagonizes GluN2B-containing NMDArs in mouse dorsal horn neurons. NEW & NOTEWORTHY Our study is the first to report that agmatine preferentially antagonizes the GluN2B receptor subunit of the N-methyl-d-aspartate (NMDA) receptor in spinal cord. The preferential targeting of GluN2B receptor is consistent with the pharmacological profile of agmatine in that it reduces chronic pain without the motor side effects commonly seen with non-subunit-selective NMDA receptor antagonists.
Collapse
Affiliation(s)
- Jonathan J Waataja
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
| | - Cristina D Peterson
- Department of Experimental and Clinical Pharmacology, University of Minnesota , Minneapolis, Minnesota
| | - Harsha Verma
- Department of Pharmaceutics, University of Minnesota , Minneapolis, Minnesota
| | | | - Philippe Séguéla
- Department of Neurology and Neurosurgery, McGill University , Montreal, Quebec , Canada
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt School of Medicine , Nashville, Tennessee
| | - George L Wilcox
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
- Department of Pharmacology, University of Minnesota , Minneapolis, Minnesota
- Department of Dermatology, University of Minnesota , Minneapolis, Minnesota
| | - Carolyn A Fairbanks
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
- Department of Experimental and Clinical Pharmacology, University of Minnesota , Minneapolis, Minnesota
- Department of Pharmaceutics, University of Minnesota , Minneapolis, Minnesota
- Department of Pharmacology, University of Minnesota , Minneapolis, Minnesota
| |
Collapse
|