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Oliveira-Lima OC, de Carvalho GA, do Prado Assunção L, Bailão AM, Ulrich H, Marques BL, de Oliveira ACP, Gomez RS, Pinto MCX. GlyT1 Inhibition by NFPS Promotes Neuroprotection in Amyloid-β-Induced Alzheimer's Disease Animal Model. Neurochem Res 2024; 49:2535-2555. [PMID: 38888830 DOI: 10.1007/s11064-024-04190-0] [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: 12/17/2023] [Revised: 04/29/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β, leading to N-methyl-D-aspartate (NMDA) receptor-dependent synaptic depression, spine elimination, and memory deficits. Glycine transporter type 1 (GlyT1) modulates glutamatergic neurotransmission via NMDA receptors (NMDAR), presenting a potential alternative therapeutic approach for AD. This study investigates the neuroprotective potential of GlyT1 inhibition in an amyloid-β-induced AD mouse model. C57BL/6 mice were treated with N-[3-([1,1-Biphenyl]-4-yloxy)-3-(4-fluorophenyl)propyl]-N-methylglycine (NFPS), a GlyT1 inhibitor, 24 h prior to intrahippocampal injection of amyloid-β. NFPS pretreatment prevented amyloid-β-induced cognitive deficits in short-term and long-term memory, evidenced by novel object recognition and spatial memory tasks. Moreover, NFPS pretreatment curbed microglial activation, astrocytic reactivity, and subsequent neuronal damage from amyloid-β injection. An extensive label-free quantitative UPLC-MSE proteomic analysis was performed on the hippocampi of mice treated with NFPS. In proteomics, KEGG enrichment analysis revealed increased in dopaminergic synapse, purine-containing compound biosynthetic process and long-term potentiation, and a reduction in Glucose catabolic process and glycolytic process pathways. The western blot analysis confirmed that NFPS treatment elevated BDNF levels, correlating with enhanced TRKB phosphorylation and mTOR activation. Moreover, NFPS treatment reduced the GluN2B expression after 6 h, which was associated with an increase on CaMKIV and CREB phosphorylation. Collectively, these findings demonstrate that GlyT1 inhibition by NFPS activates diverse neuroprotective pathways, enhancing long-term potentiation signaling and countering amyloid-β-induced hippocampal damage.
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Affiliation(s)
- Onésia Cristina Oliveira-Lima
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Gustavo Almeida de Carvalho
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Leandro do Prado Assunção
- Departamento de Bioquímica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, CEP 74690-900, Brazil
| | - Alexandre Melo Bailão
- Departamento de Bioquímica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, CEP 74690-900, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Bruno Lemes Marques
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Antônio Carlos Pinheiro de Oliveira
- Departamento de Farmacologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, Belo Horizonte-MG, 6627, 31270-901, Brazil
| | - Renato Santiago Gomez
- Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Av. Alfredo Balena, 190, Belo Horizonte-MG, 30130-100, Brazil
| | - Mauro Cunha Xavier Pinto
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil.
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Felipe R, Sarmiento-Jiménez J, Camafeita E, Vázquez J, López-Corcuera B. Role of palmitoylation on the neuronal glycine transporter GlyT2. J Neurochem 2024; 168:2056-2072. [PMID: 39032066 DOI: 10.1111/jnc.16181] [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: 02/17/2024] [Revised: 06/08/2024] [Accepted: 07/01/2024] [Indexed: 07/22/2024]
Abstract
The neuronal glycine transporter GlyT2 removes glycine from the synaptic cleft through active Na+, Cl-, and glycine cotransport contributing to the termination of the glycinergic signal as well as supplying substrate to the presynaptic terminal for the maintenance of the neurotransmitter content in synaptic vesicles. Patients with mutations in the human GlyT2 gene (SLC6A5), develop hyperekplexia or startle disease (OMIM 149400), characterized by hypertonia and exaggerated startle responses to trivial stimuli that may have lethal consequences in the neonates as a result of apnea episodes. Post-translational modifications in cysteine residues of GlyT2 are an aspect of structural interest we analyzed. Our study is compatible with a reversible and short-lived S-acylation in spinal cord membranes, detectable by biochemical and proteomics methods (acyl-Rac binding and IP-ABE) confirmed with positive and negative controls (palmitoylated and non-palmitoylated proteins). According to a short-lived modification, direct labeling using click chemistry was faint but mostly consistent. We have analyzed the physiological properties of a GlyT2 mutant lacking the cysteines with high prediction of palmitoylation and the mutant is less prone to be included in lipid rafts, an effect also observed upon treatment with the palmitoylation inhibitor 2-bromopalmitate. This work demonstrates there are determinants of lipid raft inclusion associated with the GlyT2 mutated cysteines, which are presumably modified by palmitoylation.
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Affiliation(s)
- R Felipe
- Departamento de Biología Molecular, Instituto de Biología Molecular (IUBM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
| | - J Sarmiento-Jiménez
- Departamento de Biología Molecular, Instituto de Biología Molecular (IUBM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
| | - E Camafeita
- Centro Nacional de Investigaciones Cardiovasculares. (ISCIII), Madrid, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - J Vázquez
- Centro Nacional de Investigaciones Cardiovasculares. (ISCIII), Madrid, Spain
- CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - B López-Corcuera
- Departamento de Biología Molecular, Instituto de Biología Molecular (IUBM), Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
- IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
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3
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Biswas DD, Shi Y, El Haddad L, Sethi R, Huston M, Kehoe S, Scarrow ER, Strickland LM, Pucci LA, Dhindsa JS, Hunanyan A, La Spada AR, ElMallah MK. Respiratory neuropathology in spinocerebellar ataxia type 7. JCI Insight 2024; 9:e170444. [PMID: 39053472 PMCID: PMC11457860 DOI: 10.1172/jci.insight.170444] [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: 03/20/2023] [Accepted: 07/12/2024] [Indexed: 07/27/2024] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant neurological disorder caused by deleterious CAG repeat expansion in the coding region of the ataxin 7 gene (polyQ-ataxin-7). Infantile-onset SCA7 leads to severe clinical manifestation of respiratory distress, but the exact cause of respiratory impairment remains unclear. Using the infantile-SCA7 mouse model, the SCA7266Q/5Q mouse, we examined the impact of pathological polyQ-ataxin-7 on hypoglossal (XII) and phrenic motor units. We identified the transcript profile of the medulla and cervical spinal cord and investigated the XII and phrenic nerves and the neuromuscular junctions in the diaphragm and tongue. SCA7266Q/5Q astrocytes showed significant intranuclear inclusions of ataxin-7 in the XII and putative phrenic motor nuclei. Transcriptomic analysis revealed dysregulation of genes involved in amino acid and neurotransmitter transport and myelination. Additionally, SCA7266Q/5Q mice demonstrated blunted efferent output of the XII nerve and demyelination in both XII and phrenic nerves. Finally, there was an increased number of neuromuscular junction clusters with higher expression of synaptic markers in SCA7266Q/5Q mice compared with WT controls. These preclinical findings elucidate the underlying pathophysiology responsible for impaired glial cell function and death leading to dysphagia, aspiration, and respiratory failure in infantile SCA7.
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Affiliation(s)
- Debolina D Biswas
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Yihan Shi
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Léa El Haddad
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Ronit Sethi
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Meredith Huston
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Sean Kehoe
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Evelyn R Scarrow
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Laura M Strickland
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Logan A Pucci
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Justin S Dhindsa
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Ani Hunanyan
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Albert R La Spada
- Departments of Pathology and Laboratory Medicine, Neurology, Biological Chemistry, and Neurobiology and Behavior, and
- UCI Center for Neurotherapeutics, University of California Irvine, Irvine, California, USA
| | - Mai K ElMallah
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
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Frouni I, Kim E, Shaqfah J, Bédard D, Kwan C, Belliveau S, Huot P. [ 3H]-NFPS binding to the glycine transporter 1 in the hemi-parkinsonian rat brain. Exp Brain Res 2024; 242:1203-1214. [PMID: 38526743 PMCID: PMC11078860 DOI: 10.1007/s00221-024-06815-w] [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: 01/06/2024] [Accepted: 02/23/2024] [Indexed: 03/27/2024]
Abstract
L-3,4-dihydroxyphenylalanine (L-DOPA) is the main treatment for Parkinson's disease (PD) but with long term administration, motor complications such as dyskinesia are induced. Glycine transporter 1 (GlyT1) inhibition was shown to produce an anti-dyskinetic effect in parkinsonian rats and primates, coupled with an improvement in the anti-parkinsonian action of L-DOPA. The expression of GlyT1 in the brain in the dyskinetic state remains to be investigated. Here, we quantified the levels of GlyT1 across different brain regions using [3H]-NFPS in the presence of Org-25,935. Brain sections were chosen from sham-lesioned rats, L-DOPA-naïve 6-hydroxydopamine (6-OHDA)-lesioned rats and 6-OHDA-lesioned rats exhibiting mild or severe abnormal involuntary movements (AIMs). [3H]-NFPS binding decreased in the ipsilateral and contralateral thalamus, by 28% and 41%, in 6-OHDA-lesioned rats with severe AIMs compared to sham-lesioned animals (P < 0.01 and 0.001). [3H]-NFPS binding increased by 21% in the ipsilateral substantia nigra of 6-OHDA-lesioned rats with severe AIMs compared to 6-OHDA-lesioned rats with mild AIMs (P < 0.05). [3H]-NFPS binding was lower by 19% in the contralateral primary motor cortex and by 20% in the contralateral subthalamic nucleus of 6-OHDA-lesioned rats with mild AIMs animals compared to rats with severe AIMs (both P < 0.05). The severity of AIMs scores positively correlated with [3H]-NFPS binding in the ipsilateral substantia nigra (P < 0.05), ipsilateral entopeduncular nucleus (P < 0.05) and contralateral primary motor cortex (P < 0.05). These data provide an anatomical basis to explain the efficacy of GlyT1 inhibitors in dyskinesia in PD.
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Affiliation(s)
- Imane Frouni
- Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Esther Kim
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Judy Shaqfah
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Dominique Bédard
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Cynthia Kwan
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Sébastien Belliveau
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada
| | - Philippe Huot
- Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada.
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), 3801 University St, Montreal, QC, H3A 2B4, Canada.
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.
- Movement Disorder Clinic, Division of Neurology, Department of Neurosciences, McGill University Health Centre, Montreal, QC, Canada.
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Izidoro Ribeiro R, Almeida Carvalho G, Almeida Chiareli R, Vieira de Assis Lima I, Quaglio Bellozi PM, Oliveira-Lima OC, Oliveira Giacomelli Á, Birbrair A, Santiago Gomez R, Pinheiro de Oliveira AC, Ulrich H, Cunha Xavier Pinto M. Glycine transporter-1 inhibition by NFPS promotes neuroprotection against striatal damage models. Neurosci Lett 2024; 826:137715. [PMID: 38460902 DOI: 10.1016/j.neulet.2024.137715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 03/04/2024] [Accepted: 03/06/2024] [Indexed: 03/11/2024]
Abstract
The striatum, an essential component of the brain's motor and reward systems, plays a pivotal role in a wide array of cognitive processes. Its dysfunction is a hallmark of neurodegenerative diseases like Parkinson's disease (PD) and Huntington's disease (HD), leading to profound motor and cognitive deficits. These conditions are often related to excitotoxicity, primarily due to overactivation of NMDA receptors (NMDAR). In the synaptic cleft, glycine transporter type 1 (GlyT1) controls the glycine levels, a NMDAR co-agonist, which modulates NMDAR function. This research explored the neuroprotective potential of NFPS, a GlyT1 inhibitor, in murine models of striatal injury. Employing models of neurotoxicity induced by 6-hydroxydopamine (PD model) and quinolinic acid (HD model), we assessed the effectiveness of NFPS pre-treatment in maintaining the integrity of striatal neurons and averting neuronal degeneration. The results indicated that NFPS pre-treatment conferred significant neuroprotection, reducing neuronal degeneration, protecting dopaminergic neurons, and preserving dendritic spines within the striatum. Additionally, this pre-treatment notably mitigated motor impairments resulting from striatal damage. The study revealed that GlyT1 inhibition led to substantial changes in the ratios of NMDAR subunits GluN2A/GluN1 and GluN2B/GluN1, 24 h after NFPS treatment. These findings underscore the neuroprotective efficacy of GlyT1 inhibition, proposing it as a viable therapeutic strategy for striatum-related damage.
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Affiliation(s)
- Raul Izidoro Ribeiro
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, Brazil
| | - Gustavo Almeida Carvalho
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, Brazil
| | - Raphaela Almeida Chiareli
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, Brazil
| | - Isabel Vieira de Assis Lima
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil
| | - Paula Maria Quaglio Bellozi
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil
| | | | | | - Alexander Birbrair
- Departamento de Patologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil
| | - Renato Santiago Gomez
- Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil
| | | | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo-SP, Brazil
| | - Mauro Cunha Xavier Pinto
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, Brazil.
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Baizer JS, Sherwood CC, Hof PR, Baker JF, Witelson SF. Glycine is a transmitter in the human and chimpanzee cochlear nuclei. Front Neuroanat 2024; 18:1331230. [PMID: 38425805 PMCID: PMC10902441 DOI: 10.3389/fnana.2024.1331230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/05/2024] [Indexed: 03/02/2024] Open
Abstract
Introduction Auditory information is relayed from the cochlea via the eighth cranial nerve to the dorsal and ventral cochlear nuclei (DCN, VCN). The organization, neurochemistry and circuitry of the cochlear nuclei (CN) have been studied in many species. It is well-established that glycine is an inhibitory transmitter in the CN of rodents and cats, with glycinergic cells in the DCN and VCN. There are, however, major differences in the laminar and cellular organization of the DCN between humans (and other primates) and rodents and cats. We therefore asked whether there might also be differences in glycinergic neurotransmission in the CN. Methods We studied brainstem sections from humans, chimpanzees, and cats. We used antibodies to glycine receptors (GLYR) to identify neurons receiving glycinergic input, and antibodies to the neuronal glycine transporter (GLYT2) to immunolabel glycinergic axons and terminals. We also examined archival sections immunostained for calretinin (CR) and nonphosphorylated neurofilament protein (NPNFP) to try to locate the octopus cell area (OCA), a region in the VCN that rodents has minimal glycinergic input. Results In humans and chimpanzees we found widespread immunolabel for glycine receptors in DCN and in the posterior (PVCN) and anterior (AVCN) divisions of the VCN. We found a parallel distribution of GLYT2-immunolabeled fibers and puncta. The data also suggest that, as in rodents, a region containing octopus cells in cats, humans and chimpanzees has little glycinergic input. Discussion Our results show that glycine is a major transmitter in the human and chimpanzee CN, despite the species differences in DCN organization. The sources of the glycinergic input to the CN in humans and chimpanzees are not known.
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Affiliation(s)
- Joan S. Baizer
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
| | - Chet C. Sherwood
- Department of Anthropology, The George Washington University, Washington, DC, United States
| | - Patrick R. Hof
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - James F. Baker
- Department of Neuroscience, Northwestern University Medical School, Chicago, IL, United States
| | - Sandra F. Witelson
- Department of Psychiatry and Behavioural Neurosciences, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
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Cortese K, Gagliani MC, Raiteri L. Interactions between Glycine and Glutamate through Activation of Their Transporters in Hippocampal Nerve Terminals. Biomedicines 2023; 11:3152. [PMID: 38137373 PMCID: PMC10740625 DOI: 10.3390/biomedicines11123152] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 12/24/2023] Open
Abstract
Evidence supports the pathophysiological relevance of crosstalk between the neurotransmitters Glycine and Glutamate and their close interactions; some reports even support the possibility of Glycine-Glutamate cotransmission in central nervous system (CNS) areas, including the hippocampus. Functional studies with isolated nerve terminals (synaptosomes) permit us to study transporter-mediated interactions between neurotransmitters that lead to the regulation of transmitter release. Our main aims here were: (i) to investigate release-regulating, transporter-mediated interactions between Glycine and Glutamate in hippocampal nerve terminals and (ii) to determine the coexistence of transporters for Glycine and Glutamate in these terminals. Purified synaptosomes, analyzed at the ultrastructural level via electron microscopy, were used as the experimental model. Mouse hippocampal synaptosomes were prelabeled with [3H]D-Aspartate or [3H]Glycine; the release of radiolabeled tracers was monitored with the superfusion technique. The main findings were that (i) exogenous Glycine stimulated [3H]D-Aspartate release, partly by activation of GlyT1 and in part, unusually, through GlyT2 transporters and that (ii) D-Aspartate stimulated [3H]glycine release by a process that was sensitive to Glutamate transporter blockers. Based on the features of the experimental model used, it is suggested that functional transporters for Glutamate and Glycine coexist in a small subset of hippocampal nerve terminals, a condition that may also be compatible with cotransmission; glycinergic and glutamatergic transporters exhibit different functions and mediate interactions between the neurotransmitters. It is hoped that increased information on Glutamate-Glycine interactions in different areas, including the hippocampus, will contribute to a better knowledge of drugs acting at "glycinergic" targets, currently under study in relation with different CNS pathologies.
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Affiliation(s)
- Katia Cortese
- Department of Experimental Medicine (DIMES), Cellular Electron Microscopy Lab, University of Genoa, 16132 Genoa, Italy; (K.C.); (M.C.G.)
| | - Maria Cristina Gagliani
- Department of Experimental Medicine (DIMES), Cellular Electron Microscopy Lab, University of Genoa, 16132 Genoa, Italy; (K.C.); (M.C.G.)
| | - Luca Raiteri
- Department of Pharmacy (DIFAR), Pharmacology and Toxicology Section, University of Genoa, 16148 Genoa, Italy
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Pérez-Sala D, Pajares MA. Appraising the Role of Astrocytes as Suppliers of Neuronal Glutathione Precursors. Int J Mol Sci 2023; 24:ijms24098059. [PMID: 37175763 PMCID: PMC10179008 DOI: 10.3390/ijms24098059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/25/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
The metabolism and intercellular transfer of glutathione or its precursors may play an important role in cellular defense against oxidative stress, a common hallmark of neurodegeneration. In the 1990s, several studies in the Neurobiology field led to the widely accepted notion that astrocytes produce large amounts of glutathione that serve to feed neurons with precursors for glutathione synthesis. This assumption has important implications for health and disease since a reduction in this supply from astrocytes could compromise the capacity of neurons to cope with oxidative stress. However, at first glance, this shuttling would imply a large energy expenditure to get to the same point in a nearby cell. Thus, are there additional underlying reasons for this expensive mechanism? Are neurons unable to import and/or synthesize the three non-essential amino acids that are the glutathione building blocks? The rather oxidizing extracellular environment favors the presence of cysteine (Cys) as cystine (Cis), less favorable for neuronal import. Therefore, it has also been proposed that astrocytic GSH efflux could induce a change in the redox status of the extracellular space nearby the neurons, locally lowering the Cis/Cys ratio. This astrocytic glutathione release would also increase their demand for precursors, stimulating Cis uptake, which these cells can import, further impacting the local decline of the Cis/Cys ratio, in turn, contributing to a more reduced extracellular environment and subsequently favoring neuronal Cys import. Here, we revisit the experimental evidence that led to the accepted hypothesis of astrocytes acting as suppliers of neuronal glutathione precursors, considering recent data from the Human Protein Atlas. In addition, we highlight some potential drawbacks of this hypothesis, mainly supported by heterogeneous cellular models. Finally, we outline additional and more cost-efficient possibilities by which astrocytes could support neuronal glutathione levels, including its shuttling in extracellular vesicles.
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Affiliation(s)
- Dolores Pérez-Sala
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - María A Pajares
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
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Dumontier D, Mailhes-Hamon C, Supplisson S, Dieudonné S. Neurotransmitter content heterogeneity within an interneuron class shapes inhibitory transmission at a central synapse. Front Cell Neurosci 2023; 16:1060189. [PMID: 36687523 PMCID: PMC9846633 DOI: 10.3389/fncel.2022.1060189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 12/05/2022] [Indexed: 01/06/2023] Open
Abstract
Neurotransmitter content is deemed the most basic defining criterion for neuronal classes, contrasting with the intercellular heterogeneity of many other molecular and functional features. Here we show, in the adult mouse brain, that neurotransmitter content variegation within a neuronal class is a component of its functional heterogeneity. Golgi cells (GoCs), the well-defined class of cerebellar interneurons inhibiting granule cells (GrCs), contain cytosolic glycine, accumulated by the neuronal transporter GlyT2, and GABA in various proportions. By performing acute manipulations of cytosolic GABA and glycine supply, we find that competition of glycine with GABA reduces the charge of IPSC evoked in GrCs and, more specifically, the amplitude of a slow component of the IPSC decay. We then pair GrCs recordings with optogenetic stimulations of single GoCs, which preserve the intracellular transmitter mixed content. We show that the strength and decay kinetics of GrCs IPSCs, which are entirely mediated by GABAA receptors, are negatively correlated to the presynaptic expression of GlyT2 by GoCs. We isolate a slow spillover component of GrCs inhibition that is also affected by the expression of GlyT2, leading to a 56% decrease in relative charge. Our results support the hypothesis that presynaptic loading of glycine negatively impacts the GABAergic transmission in mixed interneurons, most likely through a competition for vesicular filling. We discuss how the heterogeneity of neurotransmitter supply within mixed interneurons like the GoC class may provide a presynaptic mechanism to tune the gain of microcircuits such as the granular layer, thereby expanding the realm of their possible dynamic behaviors.
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Eulenburg V, Hülsmann S. Synergistic Control of Transmitter Turnover at Glycinergic Synapses by GlyT1, GlyT2, and ASC-1. Int J Mol Sci 2022; 23:ijms23052561. [PMID: 35269698 PMCID: PMC8909939 DOI: 10.3390/ijms23052561] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 01/25/2023] Open
Abstract
In addition to being involved in protein biosynthesis and metabolism, the amino acid glycine is the most important inhibitory neurotransmitter in caudal regions of the brain. These functions require a tight regulation of glycine concentration not only in the synaptic cleft, but also in various intracellular and extracellular compartments. This is achieved not only by confining the synthesis and degradation of glycine predominantly to the mitochondria, but also by the action of high-affinity large-capacity glycine transporters that mediate the transport of glycine across the membranes of presynaptic terminals or glial cells surrounding the synapses. Although most cells at glycine-dependent synapses express more than one transporter with high affinity for glycine, their synergistic functional interaction is only poorly understood. In this review, we summarize our current knowledge of the two high-affinity transporters for glycine, the sodium-dependent glycine transporters 1 (GlyT1; SLC6A9) and 2 (GlyT2; SLC6A5) and the alanine–serine–cysteine-1 transporter (Asc-1; SLC7A10).
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Affiliation(s)
- Volker Eulenburg
- Department for Anesthesiology and Intensive Care, Faculty of Medicine, University of Leipzig, Liebigstraße 20, D-04103 Leipzig, Germany
- Correspondence: (V.E.); (S.H.)
| | - Swen Hülsmann
- Department for Anesthesiology, University Medical Center, Georg-August University, Humboldtallee 23, D-37073 Göttingen, Germany
- Correspondence: (V.E.); (S.H.)
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11
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Bozzo M, Costa S, Obino V, Bachetti T, Marcenaro E, Pestarino M, Schubert M, Candiani S. Functional Conservation and Genetic Divergence of Chordate Glycinergic Neurotransmission: Insights from Amphioxus Glycine Transporters. Cells 2021; 10:cells10123392. [PMID: 34943900 PMCID: PMC8699752 DOI: 10.3390/cells10123392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 11/24/2022] Open
Abstract
Glycine is an important neurotransmitter in vertebrates, performing both excitatory and inhibitory actions. Synaptic levels of glycine are tightly controlled by the action of two glycine transporters, GlyT1 and GlyT2, located on the surface of glial cells and neurons, respectively. Only limited information is available on glycinergic neurotransmission in invertebrates, and the evolution of glycinergic neurotransmission is poorly understood. Here, by combining phylogenetic and gene expression analyses, we characterized the glycine transporter complement of amphioxus, an important invertebrate model for studying the evolution of chordates. We show that amphioxus possess three glycine transporter genes. Two of these (GlyT2.1 and GlyT2.2) are closely related to GlyT2 of vertebrates, whereas the third (GlyT) is a member of an ancestral clade of deuterostome glycine transporters. GlyT2.2 expression is predominantly non-neural, whereas GlyT and GlyT2.1 are widely expressed in the amphioxus nervous system and are differentially expressed, respectively, in neurons and glia. Vertebrate glycinergic neurons express GlyT2 and glia GlyT1, suggesting that the evolution of the chordate glycinergic system was accompanied by a paralog-specific inversion of gene expression. Despite this genetic divergence between amphioxus and vertebrates, we found strong evidence for conservation in the role glycinergic neurotransmission plays during larval swimming, the implication being that the neural networks controlling the rhythmic movement of chordate bodies may be homologous.
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Affiliation(s)
- Matteo Bozzo
- Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, 16132 Genoa, Italy; (S.C.); (T.B.); (M.P.)
- Dipartimento di Medicina Sperimentale (DIMES), Università degli Studi di Genova, 16132 Genoa, Italy; (V.O.); (E.M.)
- Correspondence: (M.B.); (S.C.); Tel.: +39-010-335-8043 (M.B.); +39-010-335-8051 (S.C.)
| | - Simone Costa
- Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, 16132 Genoa, Italy; (S.C.); (T.B.); (M.P.)
| | - Valentina Obino
- Dipartimento di Medicina Sperimentale (DIMES), Università degli Studi di Genova, 16132 Genoa, Italy; (V.O.); (E.M.)
| | - Tiziana Bachetti
- Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, 16132 Genoa, Italy; (S.C.); (T.B.); (M.P.)
| | - Emanuela Marcenaro
- Dipartimento di Medicina Sperimentale (DIMES), Università degli Studi di Genova, 16132 Genoa, Italy; (V.O.); (E.M.)
| | - Mario Pestarino
- Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, 16132 Genoa, Italy; (S.C.); (T.B.); (M.P.)
| | - Michael Schubert
- Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Institut de la Mer de Villefranche, Sorbonne Université, CNRS, 06230 Villefranche-sur-Mer, France;
| | - Simona Candiani
- Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, 16132 Genoa, Italy; (S.C.); (T.B.); (M.P.)
- Correspondence: (M.B.); (S.C.); Tel.: +39-010-335-8043 (M.B.); +39-010-335-8051 (S.C.)
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12
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Hoffmann C, Evcüman S, Neumaier F, Zlatopolskiy BD, Humpert S, Bier D, Holschbach M, Schulze A, Endepols H, Neumaier B. [ 18F]ALX5406: A Brain-Penetrating Prodrug for GlyT1-Specific PET Imaging. ACS Chem Neurosci 2021; 12:3335-3346. [PMID: 34449193 DOI: 10.1021/acschemneuro.1c00284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Selective inhibition of glycine transporter 1 (GlyT1) has emerged as a potential approach to alleviate N-methyl-d-aspartate receptor (NMDAR) hypofunction in patients with schizophrenia and cognitive decline. ALX5407 is a potent and selective inhibitor of GlyT1 derived from the metabolic intermediate sarcosine (N-methylglycine) that showed antipsychotic potential in a number of animal models. Whereas clinical application of ALX5407 is limited by adverse effects on motor performance and respiratory function, a suitably radiolabeled drug could represent a promising PET tracer for the visualization of GlyT1 in the brain. Herein, [18F]ALX5407 and the corresponding methyl ester, [18F]ALX5406, were prepared by alcohol-enhanced copper mediated radiofluorination and studied in vitro in rat brain slices and in vivo in normal rats. [18F]ALX5407 demonstrated accumulation consistent with the distribution of GlyT1 in in vitro autoradiographic studies but no brain uptake in μPET experiments in naı̈ve rats. In contrast, the methyl ester [18F]ALX5406 rapidly entered the brain and was enzymatically transformed into [18F]ALX5407, resulting in a regional accumulation pattern consistent with GlyT1 specific binding. We conclude that [18F]ALX5406 is a promising and easily accessible PET probe for preclinical in vivo imaging of GlyT1 in the brain.
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Affiliation(s)
- Chris Hoffmann
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Sibel Evcüman
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Felix Neumaier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Boris D. Zlatopolskiy
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Swen Humpert
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Dirk Bier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Marcus Holschbach
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Annette Schulze
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Heike Endepols
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
- Nuclear Medicine Department, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Bernd Neumaier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
- Max Planck Institute of Metabolism Research, 50931 Cologne, Germany
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13
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Inhibition of Glycine Re-Uptake: A Potential Approach for Treating Pain by Augmenting Glycine-Mediated Spinal Neurotransmission and Blunting Central Nociceptive Signaling. Biomolecules 2021; 11:biom11060864. [PMID: 34200954 PMCID: PMC8230656 DOI: 10.3390/biom11060864] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/07/2021] [Accepted: 06/08/2021] [Indexed: 12/23/2022] Open
Abstract
Among the myriad of cellular and molecular processes identified as contributing to pathological pain, disinhibition of spinal cord nociceptive signaling to higher cortical centers plays a critical role. Importantly, evidence suggests that impaired glycinergic neurotransmission develops in the dorsal horn of the spinal cord in inflammatory and neuropathic pain models and is a key maladaptive mechanism causing mechanical hyperalgesia and allodynia. Thus, it has been hypothesized that pharmacological agents capable of augmenting glycinergic tone within the dorsal horn may be able to blunt or block aberrant nociceptor signaling to the brain and serve as a novel class of analgesics for various pathological pain states. Indeed, drugs that enhance dysfunctional glycinergic transmission, and in particular inhibitors of the glycine transporters (GlyT1 and GlyT2), are generating widespread interest as a potential class of novel analgesics. The GlyTs are Na+/Cl−-dependent transporters of the solute carrier 6 (SLC6) family and it has been proposed that the inhibition of them presents a possible mechanism by which to increase spinal extracellular glycine concentrations and enhance GlyR-mediated inhibitory neurotransmission in the dorsal horn. Various inhibitors of both GlyT1 and GlyT2 have demonstrated broad analgesic efficacy in several preclinical models of acute and chronic pain, providing promise for the approach to deliver a first-in-class non-opioid analgesic with a mechanism of action differentiated from current standard of care. This review will highlight the therapeutic potential of GlyT inhibitors as a novel class of analgesics, present recent advances reported for the field, and discuss the key challenges associated with the development of a GlyT inhibitor into a safe and effective agent to treat pain.
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14
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Benito-Muñoz C, Perona A, Felipe R, Pérez-Siles G, Núñez E, Aragón C, López-Corcuera B. Structural Determinants of the Neuronal Glycine Transporter 2 for the Selective Inhibitors ALX1393 and ORG25543. ACS Chem Neurosci 2021; 12:1860-1872. [PMID: 34003005 PMCID: PMC8691691 DOI: 10.1021/acschemneuro.0c00602] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
![]()
The
neuronal glycine transporter GlyT2 modulates inhibitory glycinergic
neurotransmission by controlling the extracellular concentration of
synaptic glycine and the supply of neurotransmitter to the presynaptic
terminal. Spinal cord glycinergic neurons present in the dorsal horn
diminish their activity in pathological pain conditions and behave
as gate keepers of the touch-pain circuitry. The pharmacological blockade
of GlyT2 reduces the progression of the painful signal to rostral
areas of the central nervous system by increasing glycine extracellular
levels, so it has analgesic action. O-[(2-benzyloxyphenyl-3-fluorophenyl)methyl]-l-serine (ALX1393) and N-[[1-(dimethylamino)cyclopentyl]methyl]-3,5-dimethoxy-4-(phenylmethoxy)benzamide
(ORG25543) are two selective GlyT2 inhibitors with nanomolar affinity
for the transporter and analgesic effects in pain animal models, although
with deficiencies which preclude further clinical development. In
this report, we performed a comparative ligand docking of ALX1393
and ORG25543 on a validated GlyT2 structural model including all ligand
sites constructed by homology with the crystallized dopamine transporter
from Drosophila melanogaster. Molecular dynamics
simulations and energy analysis of the complex and functional analysis
of a series of point mutants permitted to determine the structural
determinants of ALX1393 and ORG25543 discrimination by GlyT2. The
ligands establish simultaneous contacts with residues present in transmembrane
domains 1, 3, 6, and 8 and block the transporter in outward-facing
conformation and hence inhibit glycine transport. In addition, differential
interactions of ALX1393 with the cation bound at Na1 site and ORG25543
with TM10 define the differential sites of the inhibitors and explain
some of their individual features. Structural information about the
interactions with GlyT2 may provide useful tools for new drug discovery.
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Affiliation(s)
- Cristina Benito-Muñoz
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Almudena Perona
- Departamento de Química en Ciencias Farmacéuticas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Raquel Felipe
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Gonzalo Pérez-Siles
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Enrique Núñez
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Carmen Aragón
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- IdiPAZ-Hospital Universitario La Paz, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Biología Molecular “Severo Ochoa” Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- IdiPAZ-Hospital Universitario La Paz, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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15
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Feng WX, Zhuo XW, Liu ZM, Li JW, Zhang WH, Wu Y, Han TL, Fang F. Case Report: A Variant Non-ketotic Hyperglycinemia With GLRX5 Mutations: Manifestation of Deficiency of Activities of the Respiratory Chain Enzymes. Front Genet 2021; 12:605778. [PMID: 34054912 PMCID: PMC8155699 DOI: 10.3389/fgene.2021.605778] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 04/08/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: Variant non-ketotic hyperglycinaemia (NKH) is a rare disorder characterized by variable clinical, biochemical, and imaging features. The variant form of NKH is rare and characterized by variable clinical, biochemical and imaging features. Subjects: Herein, we report a girl with variant NKH with two mutations in glutaredoxin 5 (GLRX5), which has been described in only three patients. Results: The clinical and biochemical phenotypes of the patient are also described. She suffered from developmental regression associated with spasticity, developmental delay, anemia and optic atrophy. The mitochondrial leukoencephalopathy was used to designate these disorders. An increased T2 signal from the medulla oblongata to the C6 spinal region was also observed on spinal cord MRI. Tandem mass analysis of a dried blood sample revealed elevated levels of glycine. The patient has two compound heterozygous mutations (c.151_153 del AAG and c.196C>T) in the GLRX5 gene. The c.196C>T mutation led to a stop codon (p.Q66Ter). Activities of mitochondrial respiratory chain (MRC) complexes II+III in the patient's fibroblasts were abnormal. Conclusions: We present the case of a girl with variant NKH who manifested spasticity and bilateral cavitating leukoencephalopathy. The patient had a deficiency of a respiratory chain enzyme, and this is the first report. Genetic testing is important for physicians to evaluate suspected variant NKH patients and to provide proper genetic counseling.
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Affiliation(s)
- Wei-Xing Feng
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Xiu-Wei Zhuo
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Zhi-Mei Liu
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Jiu-Wei Li
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Wei-Hua Zhang
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Yun Wu
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Tong-Li Han
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
| | - Fang Fang
- Neurology Department, National Center for Children's Health China, Beijing Children Hospital Affiliated to Capital Medical University, Beijing, China
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16
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Rescue of two trafficking-defective variants of the neuronal glycine transporter GlyT2 associated to hyperekplexia. Neuropharmacology 2021; 189:108543. [PMID: 33794243 DOI: 10.1016/j.neuropharm.2021.108543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 11/21/2022]
Abstract
Hyperekplexia is a rare sensorimotor syndrome characterized by pathological startle reflex in response to unexpected trivial stimuli for which there is no specific treatment. Neonates suffer from hypertonia and are at high risk of sudden death due to apnea episodes. Mutations in the human SLC6A5 gene encoding the neuronal glycine transporter GlyT2 may disrupt the inhibitory glycinergic neurotransmission and cause a presynaptic form of the disease. The phenotype of missense mutations giving rise to protein misfolding but maintaining residual activity could be rescued by facilitating folding or intracellular trafficking. In this report, we characterized the trafficking properties of two mutants associated with hyperekplexia (A277T and Y707C, rat numbering). Transporter molecules were partially retained in the endoplasmic reticulum showing increased interaction with the endoplasmic reticulum chaperone calnexin. One transporter variant had export difficulties and increased ubiquitination levels, suggestive of enhanced endoplasmic reticulum-associated degradation. However, the two mutant transporters were amenable to correction by calnexin overexpression. Within the search for compounds capable of rescuing mutant phenotypes, we found that the arachidonic acid derivative N-arachidonoyl glycine can rescue the trafficking defects of the two variants in heterologous cells and rat brain cortical neurons. N-arachidonoyl glycine improves the endoplasmic reticulum output by reducing the interaction transporter/calnexin, increasing membrane expression and improving transport activity in a comparable way as the well-established chemical chaperone 4-phenyl-butyrate. This work identifies N-arachidonoyl glycine as a promising compound with potential for hyperekplexia therapy.
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17
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Jiménez E, Fornés A, Felipe R, Núñez E, Aragón C, López-Corcuera B. Calcium-Dependent Regulation of the Neuronal Glycine Transporter GlyT2 by M2 Muscarinic Acetylcholine Receptors. Neurochem Res 2021; 47:190-203. [PMID: 33765249 DOI: 10.1007/s11064-021-03298-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/23/2021] [Accepted: 03/12/2021] [Indexed: 10/21/2022]
Abstract
The neuronal glycine transporter GlyT2 modulates inhibitory glycinergic neurotransmission and plays a key role in regulating nociceptive signal progression. The cholinergic system acting through muscarinic acetylcholine receptors (mAChRs) also mediates important regulations of nociceptive transmission being the M2 subtype the most abundantly expressed in the spinal cord. Here we studied the effect of M2 mAChRs stimulation on GlyT2 function co-expressed in a heterologous system with negligible levels of muscarinic receptor activity. We found GlyT2 is down-regulated by carbachol in a calcium-dependent manner. Different components involved in cell calcium homeostasis were analysed to establish a role in the mechanism of GlyT2 inhibition. GlyT2 down-regulation by carbachol was increased by thapsigargin and reduced by internal store depletion, although calcium release from endoplasmic reticulum or mitochondria had a minor role on GlyT2 inhibition. Our results are consistent with a GlyT2 sensitivity to intracellular calcium mobilized by M2 mAChRs in the subcortical area of the plasma membrane. A crucial role of the plasma membrane sodium calcium exchanger NCX is proposed.
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Affiliation(s)
- Esperanza Jiménez
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Amparo Fornés
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Novartis Farmacéutica S.A., Basel, Switzerland
| | - Raquel Felipe
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Enrique Núñez
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Carmen Aragón
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain.,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049, Madrid, Spain. .,IdiPAZ-Hospital Universitario La Paz, Madrid, Spain.
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18
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Pharmacological Evidence on Augmented Antiallodynia Following Systemic Co-Treatment with GlyT-1 and GlyT-2 Inhibitors in Rat Neuropathic Pain Model. Int J Mol Sci 2021; 22:ijms22052479. [PMID: 33804568 PMCID: PMC7957511 DOI: 10.3390/ijms22052479] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/19/2021] [Accepted: 02/25/2021] [Indexed: 12/16/2022] Open
Abstract
The limited effect of current medications on neuropathic pain (NP) has initiated large efforts to develop effective treatments. Animal studies showed that glycine transporter (GlyT) inhibitors are promising analgesics in NP, though concerns regarding adverse effects were raised. We aimed to study NFPS and Org-25543, GlyT-1 and GlyT-2 inhibitors, respectively and their combination in rat mononeuropathic pain evoked by partial sciatic nerve ligation. Cerebrospinal fluid (CSF) glycine content was also determined by capillary electrophoresis. Subcutaneous (s.c.) 4 mg/kg NFPS or Org-25543 showed analgesia following acute administration (30-60 min). Small doses of each compound failed to produce antiallodynia up to 180 min after the acute administration. However, NFPS (1 mg/kg) produced antiallodynia after four days of treatment. Co-treatment with subanalgesic doses of NFPS (1 mg/kg) and Org-25543 (2 mg/kg) produced analgesia at 60 min and thereafter meanwhile increased significantly the CSF glycine content. This combination alleviated NP without affecting motor function. Test compounds failed to activate G-proteins in spinal cord. To the best of our knowledge for the first time we demonstrated augmented analgesia by combining GlyT-1 and 2 inhibitors. Increased CSF glycine content supports involvement of glycinergic system. Combining selective GlyT inhibitors or developing non-selective GlyT inhibitors might have therapeutic value in NP.
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19
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Pei JC, Luo DZ, Gau SS, Chang CY, Lai WS. Directly and Indirectly Targeting the Glycine Modulatory Site to Modulate NMDA Receptor Function to Address Unmet Medical Needs of Patients With Schizophrenia. Front Psychiatry 2021; 12:742058. [PMID: 34658976 PMCID: PMC8517243 DOI: 10.3389/fpsyt.2021.742058] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/02/2021] [Indexed: 12/30/2022] Open
Abstract
Schizophrenia is a severe mental illness that affects ~1% of the world's population. It is clinically characterized by positive, negative, and cognitive symptoms. Currently available antipsychotic medications are relatively ineffective in improving negative and cognitive deficits, which are related to a patient's functional outcomes and quality of life. Negative symptoms and cognitive deficits are unmet by the antipsychotic medications developed to date. In recent decades, compelling animal and clinical studies have supported the NMDA receptor (NMDAR) hypofunction hypothesis of schizophrenia and have suggested some promising therapeutic agents. Notably, several NMDAR-enhancing agents, especially those that function through the glycine modulatory site (GMS) of NMDAR, cause significant reduction in psychotic and cognitive symptoms in patients with schizophrenia. Given that the NMDAR-mediated signaling pathway has been implicated in cognitive/social functions and that GMS is a potential therapeutic target for enhancing the activation of NMDARs, there is great interest in investigating the effects of direct and indirect GMS modulators and their therapeutic potential. In this review, we focus on describing preclinical and clinical studies of direct and indirect GMS modulators in the treatment of schizophrenia, including glycine, D-cycloserine, D-serine, glycine transporter 1 (GlyT1) inhibitors, and D-amino acid oxidase (DAO or DAAO) inhibitors. We highlight some of the most promising recently developed pharmacological compounds designed to either directly or indirectly target GMS and thus augment NMDAR function to treat the cognitive and negative symptoms of schizophrenia. Overall, the current findings suggest that indirectly targeting of GMS appears to be more beneficial and leads to less adverse effects than direct targeting of GMS to modulate NMDAR functions. Indirect GMS modulators, especially GlyT1 inhibitors and DAO inhibitors, open new avenues for the treatment of unmet medical needs for patients with schizophrenia.
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Affiliation(s)
- Ju-Chun Pei
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Da-Zhong Luo
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Shiang-Shin Gau
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Chia-Yuan Chang
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
| | - Wen-Sung Lai
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
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20
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Varga E, Farkas E, Zséli G, Kádár A, Venczel A, Kővári D, Németh D, Máté Z, Erdélyi F, Horváth A, Szenci O, Watanabe M, Lechan RM, Gereben B, Fekete C. Thyrotropin-Releasing-Hormone-Synthesizing Neurons of the Hypothalamic Paraventricular Nucleus Are Inhibited by Glycinergic Inputs. Thyroid 2019; 29:1858-1868. [PMID: 31659941 DOI: 10.1089/thy.2019.0357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: Glycine is a classical neurotransmitter that has role in both inhibitory and excitatory synapses. To understand whether glycinergic inputs are involved in the regulation of the hypophysiotropic thyrotropin-releasing hormone (TRH) neurons, the central controllers of the hypothalamic-pituitary-thyroid axis, the glycinergic innervation of the TRH neurons was studied in the hypothalamic paraventricular nucleus (PVN). Methods: Double-labeling immunocytochemistry and patch-clamp electrophysiology were used to determine the role of glycinergic neurons in the regulation of TRH neurons in the PVN. Anterograde and retrograde tracing methods were used to determine the sources of the glycinergic input of TRH neurons. Results: Glycine transporter-2 (GLYT2), a marker of glycinergic neurons, containing axons were found to establish symmetric type of synapses on TRH neurons in the PVN. Furthermore, glycine receptor immunoreactivity was observed in these TRH neurons. The raphe magnus (RMg) and the ventrolateral periaqueductal gray (VLPAG) were found to be the exclusive sources of the glycinergic innervation of the TRH neurons within the PVN. Patch-clamp electrophysiology using sections of TRH-IRES-tdTomato mice showed that glycine hyperpolarized the TRH neurons and completely blocked the firing of these neurons. Glycine also markedly hyperpolarized the TRH neurons in the presence of tetrodotoxin demonstrating the direct effect of glycine. In more than 60% of the TRH neurons, spontaneous inhibitory postsynaptic currents (sIPSCs) were observed, even after the pharmacological inhibition of glutamatergic and GABAergic neuronal transmission. The glycine antagonist, strychnine, almost completely abolished these sIPSCs, demonstrating the inhibitory nature of the glycinergic input of TRH neurons. Conclusions: These data demonstrate that TRH neurons in the PVN receive glycinergic inputs from the RMg and the VLPAG. The symmetric type of synaptic connection and the results of the electrophysiological experiments demonstrate the inhibitory nature of these inputs.
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Affiliation(s)
- Edina Varga
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Erzsébet Farkas
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Györgyi Zséli
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Andrea Kádár
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Alexandra Venczel
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dóra Kővári
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dorottya Németh
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zoltán Máté
- Medical Gene Technology Unit, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ferenc Erdélyi
- Medical Gene Technology Unit, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - András Horváth
- Department and Clinic for Production Animals, University of Veterinary Medicine Budapest, Üllő, Dóra Major, Hungary
- MTA-SZIE Large Animal Clinical Research Group, Üllő, Dóra major, Hungary
| | - Ottó Szenci
- Department and Clinic for Production Animals, University of Veterinary Medicine Budapest, Üllő, Dóra Major, Hungary
- MTA-SZIE Large Animal Clinical Research Group, Üllő, Dóra major, Hungary
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Ronald M Lechan
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Csaba Fekete
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts
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21
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Li W, Zuo W, Wu W, Zuo QK, Fu R, Wu L, Zhang H, Ndukwe M, Ye JH. Activation of glycine receptors in the lateral habenula rescues anxiety- and depression-like behaviors associated with alcohol withdrawal and reduces alcohol intake in rats. Neuropharmacology 2019; 157:107688. [PMID: 31254534 PMCID: PMC6677595 DOI: 10.1016/j.neuropharm.2019.107688] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/18/2019] [Accepted: 06/26/2019] [Indexed: 01/03/2023]
Abstract
The lateral habenula (LHb) is activated by a range of aversive states including those related to alcohol withdrawal and has glycine receptors (GlyRs), a sensitive target of alcohol. However, whether GlyRs in the LHb contribute to alcohol-related behaviors is unknown. Here, we report that rats experiencing withdrawal from chronic alcohol consumption showed higher anxiety and sensitivity to stress compared to their alcohol-naïve counterparts. Intra-LHb injection of glycine attenuated these aberrant behaviors and reduced alcohol intake upon alcohol re-access. Glycine's effect was blocked by strychnine, a GlyR antagonist, indicating that it was mediated by strychnine-sensitive GlyRs. Conversely, intra-LHb strychnine elicited anxiety- and depression-like behaviors in Naïve rats but not in withdrawal rats. Additionally, both the frequency and the amplitude of the spontaneous IPSCs were lower in LHb neurons in slices of withdrawal rats compared to naïve rats. Also, there were sporadic strychnine-sensitive synaptic events in some LHb neurons. Bath perfusion of strychnine induced a depolarizing inward current and increased action potential firings in LHb neurons. By contrast, bath perfusion of glycine or sarcosine, a glycine transporter subtype 1 inhibitor, inhibited LHb activity. Collectively, these data reveal that LHb neurons are under the tonic glycine inhibition both in physiological and pathological conditions. Activation of GlyRs reverses LHb hyperactivity, alleviates aberrant behaviors, and reduces alcohol intake, thus highlighting the GlyRs in the LHb as a potential therapeutic target for alcohol-use disorders.
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Affiliation(s)
- Wenting Li
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Wanhong Zuo
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Wei Wu
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Qi Kang Zuo
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Rao Fu
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Liangzhi Wu
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Haifeng Zhang
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Michael Ndukwe
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA
| | - Jiang-Hong Ye
- Department of Anesthesiology, Pharmacology, & Physiology, and Neuroscience, Rutgers, The State University of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, USA.
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22
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McLaughlin C, Clements J, Oprişoreanu AM, Sylantyev S. The role of tonic glycinergic conductance in cerebellar granule cell signalling and the effect of gain-of-function mutation. J Physiol 2019; 597:2457-2481. [PMID: 30875431 DOI: 10.1113/jp277626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 03/14/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS A T258F mutation of the glycine receptor increases the receptor affinity to endogenous agonists, modifies single-channel conductance and shapes response decay kinetics. Glycine receptors of cerebellar granule cells play their functional role not continuously, but when the granule cell layer starts receiving a high amount of excitatory inputs. Despite their relative scarcity, tonically active glycine receptors of cerebellar granule cells make a significant impact on action potential generation and inter-neuronal crosstalk, and modulate synaptic plasticity in neural networks; extracellular glycine increases probability of postsynaptic response occurrence acting at NMDA receptors and decreases this probability acting at glycine receptors. Tonic conductance through glycine receptors of cerebellar granule cells is a yet undiscovered element of the biphasic mechanism that regulates processing of sensory inputs in the cerebellum. A T258F point mutation disrupts this biphasic mechanism, thus illustrating the possible role of the gain-of-function mutations of the glycine receptor in development of neural pathologies. ABSTRACT Functional glycine receptors (GlyRs) have been repeatedly detected in cerebellar granule cells (CGCs), where they deliver exclusively tonic inhibitory signals. The functional role of this signalling, however, remains unclear. Apart from that, there is accumulating evidence of the important role of GlyRs in cerebellar structures in development of neural pathologies such as hyperekplexia, which can be triggered by GlyR gain-of-function mutations. In this research we initially tested functional properties of GlyRs, carrying the yet understudied T258F gain-of-function mutation, and found that this mutation makes significant modifications in GlyR response to endogenous agonists. Next, we clarified the role of tonic GlyR conductance in neuronal signalling generated by single CGCs and by neural networks in cell cultures and in living cerebellar tissue of C57Bl-6J mice. We found that GlyRs of CGCs deliver a significant amount of tonic inhibition not continuously, but when the cerebellar granule layer starts receiving substantial excitatory input. Under these conditions tonically active GlyRs become a part of neural signalling machinery allowing generation of action potential (AP) bursts of limited length in response to sensory-evoked signals. GlyRs of CGCs support a biphasic modulatory mechanism which enhances AP firing when excitatory input intensity is low, but suppresses it when excitatory input rises to a certain critical level. This enables one of the key functions of the CGC layer: formation of sensory representations and their translation into motor output. Finally, we have demonstrated that the T258F mutation in CGC GlyRs modifies single-cell and neural network signalling, and breaks a biphasic modulation of the AP-generating machinery.
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Affiliation(s)
- Catherine McLaughlin
- Gene Therapy Group, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - John Clements
- The John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, ACT 2601, Australia
| | - Ana-Maria Oprişoreanu
- Center for Discovery Brain Sciences, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Sergiy Sylantyev
- Center for Clinical Brain Sciences, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
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23
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Merk W, Kucia K, Mędrala T, Kowalczyk M, Owczarek A, Kowalski J. Association study of the excitatory amino acid transporter 2 (EAAT2) and glycine transporter 1 (GlyT1) gene polymorphism with schizophrenia in a Polish population. Neuropsychiatr Dis Treat 2019; 15:989-1000. [PMID: 31118638 PMCID: PMC6499478 DOI: 10.2147/ndt.s194924] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 02/14/2019] [Indexed: 01/28/2023] Open
Abstract
Background: Excitatory amino acid transporter 2 encoded by SLC1A2 is responsible for approximately 90% of glutamate uptake. Glycine transporter 1, encoded by SLC6A9, is responsible for maintaining a low concentration of the N-methyl-D-aspartate receptor (NMDAR) co-agonist - glycine in the synaptic cleft, suggesting its participation in the development of the NMDARs hypofunction described in schizophrenia. Aim: The aim of this study was to evaluate whether the functional polymorphism-181 A/C (rs4354668) of the SLC1A2 and the rs2486001 (IVS3+411 G/A) in the SLC6A9 are involved in schizophrenia development and its clinical picture in the Polish population. Methods: The study group consisted of 393 unrelated Caucasian patients (157 [39.9%] females and 236 [60.1%] males; mean age 41±12) diagnosed with schizophrenia according to the DSM-5, and 462 healthy controls. The results of the Positive and Negative Syndrome Scale (PANSS) were presented in the five-dimensional model. Polymorphisms of SLC1A2 and SLC6A9 were genotyped with the use of PCR-RFLP assay. Results: There were no statistically significant differences in the frequency of genotypes and alleles between the patients and controls for SLC1A2 and SLC6A9 polymorphisms in either the entire sample or after stratification according to gender. In the haplotype analysis, men with CA haplotype had more than 1.5 higher risk to develop schizophrenia than women (OR=1.63 [95% CI=1.17-2.27, p<0.05]). The influence of gender, genotypes of both analyzed polymorphisms and gender x genotype interactions on individual dimensions of the PANSS scale has not been observed. Also, there was no association of either polymorphism with suicide attempts. Conclusion: The results of the present study did not indicate an association of polymorphism-181 A/C (rs4354668) in SLC1A2 and rs2486001 in SLC6A9 with onset of schizophrenia and its psychopathology in a Polish population.
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Affiliation(s)
- Wojciech Merk
- Department of Psychiatry and Psychotherapy, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Krzysztof Kucia
- Department of Psychiatry and Psychotherapy, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Tomasz Mędrala
- Department of Psychiatry and Psychotherapy, School of Medicine in Katowice, Medical University of Silesia, Katowice, Poland
| | - Małgorzata Kowalczyk
- Department of Medical Genetics, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Katowice, Poland
| | - Aleksander Owczarek
- Division of Statistics, Department of Instrumental Analysis, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Katowice, Poland.,Department of Instrumental Analysis, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Katowice, Poland
| | - Jan Kowalski
- Department of Medical Genetics, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Katowice, Poland
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24
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Zafra F, Ibáñez I, Bartolomé-Martín D, Piniella D, Arribas-Blázquez M, Giménez C. Glycine Transporters and Its Coupling with NMDA Receptors. ADVANCES IN NEUROBIOLOGY 2018; 16:55-83. [PMID: 28828606 DOI: 10.1007/978-3-319-55769-4_4] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Glycine plays two roles in neurotransmission. In caudal areas like the spinal cord and the brainstem, it acts as an inhibitory neurotransmitter, but in all regions of the CNS, it also works as a co-agonist with L-glutamate at N-methyl-D-aspartate receptors (NMDARs). The glycine fluxes in the CNS are regulated by two specific transporters for glycine, GlyT1 and GlyT2, perhaps with the cooperation of diverse neutral amino acid transporters like Asc-1 or SNAT5/SN2. While GlyT2 and Asc-1 are neuronal proteins, GlyT1 and SNAT5 are mainly astrocytic, although neuronal forms of GlyT1 also exist. GlyT1 has attracted considerable interest from the medical community and the pharmaceutical industry since compelling evidence indicates a clear association with the functioning of NMDARs, whose activity is decreased in various psychiatric illnesses. By controlling extracellular glycine, transporter inhibitors might potentiate the activity of NMDARs without activating excitotoxic processes. Physiologically, GlyT1 is a central actor in the cross talk between glutamatergic, glycinergic, dopaminergic, and probably other neurotransmitter systems. Many of these relationships begin to be unraveled by studies performed in recent years using genetic and pharmacological models. These studies are also clarifying the interactions between glycine, glycine transporters, and other co-agonists of the glycine site of NMDARs like D-serine. These findings are also relevant to understand the pathophysiology of devastating diseases like schizophrenia, depression, anxiety, epilepsy, stroke, and chronic pain.
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Affiliation(s)
- Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
| | - Ignacio Ibáñez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - David Bartolomé-Martín
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Piniella
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Marina Arribas-Blázquez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Cecilio Giménez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, C / Nicolás Cabrera, 1, 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras and IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
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25
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Winters BL, Rawling T, Vandenberg RJ, Christie MJ, Bhola RF, Imlach WL. Activity of novel lipid glycine transporter inhibitors on synaptic signalling in the dorsal horn of the spinal cord. Br J Pharmacol 2018; 175:2337-2347. [PMID: 29500820 DOI: 10.1111/bph.14189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 02/03/2018] [Accepted: 02/06/2018] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE Inhibitory neurotransmission plays an important role in controlling excitability within nociceptive circuits of the spinal cord dorsal horn. Loss of inhibitory signalling is thought to contribute to the development of pathological pain. Preclinical studies suggest that increasing inhibitory glycinergic signalling is a good therapeutic strategy for treating pain. One approach to increase synaptic glycine is to inhibit the activity of the glycine transporter 2 (GlyT2) on inhibitory nerve terminals. These transporters are involved in regulating glycine concentrations and recycling glycine into presynaptic terminals. Inhibiting activity of GlyT2 increases synaptic glycine, which decreases excitability in nociceptive circuits and provides analgesia in neuropathic and inflammatory pain models. EXPERIMENTAL APPROACH We investigated the effects of reversible and irreversible GlyT2 inhibitors on inhibitory glycinergic and NMDA receptor-mediated excitatory neurotransmission in the rat dorsal horn. The effect of these drugs on synaptic signalling was determined using patch-clamp electrophysiology techniques to measure glycine- and NMDA-mediated postsynaptic currents in spinal cord slices in vitro. KEY RESULTS We compared activity of four compounds that increase glycinergic tone with a corresponding increase in evoked glycinergic postsynaptic currents. These compounds did not deplete synaptic glycine release over time. Interestingly, none of these compounds increased glycine-mediated excitatory signalling through NMDA receptors. The results suggest that these compounds preferentially inhibit GlyT2 over G1yT1 with no potentiation of the glycine receptor and without inducing spillover from inhibitory to excitatory synapses. CONCLUSIONS AND IMPLICATIONS GlyT2 inhibitors increase inhibitory neurotransmission in the dorsal horn and have potential as pain therapeutics. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
- Bryony L Winters
- Pain Management Research Institute, Kolling Institute of Medical Research, The University of Sydney, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Tristan Rawling
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Robert J Vandenberg
- Discipline of Pharmacology, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Macdonald J Christie
- Discipline of Pharmacology, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Rebecca F Bhola
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Wendy L Imlach
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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26
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Zeilhofer HU, Acuña MA, Gingras J, Yévenes GE. Glycine receptors and glycine transporters: targets for novel analgesics? Cell Mol Life Sci 2018; 75:447-465. [PMID: 28791431 PMCID: PMC11105467 DOI: 10.1007/s00018-017-2622-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/14/2017] [Accepted: 08/04/2017] [Indexed: 01/29/2023]
Abstract
Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized-among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties.
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Affiliation(s)
- Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | | | - Gonzalo E Yévenes
- Department of Physiology, University of Concepción, Concepción, Chile
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27
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Ghirardini E, Wadle SL, Augustin V, Becker J, Brill S, Hammerich J, Seifert G, Stephan J. Expression of functional inhibitory neurotransmitter transporters GlyT1, GAT-1, and GAT-3 by astrocytes of inferior colliculus and hippocampus. Mol Brain 2018; 11:4. [PMID: 29370841 PMCID: PMC5785846 DOI: 10.1186/s13041-018-0346-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/03/2018] [Indexed: 12/18/2022] Open
Abstract
Neuronal inhibition is mediated by glycine and/or GABA. Inferior colliculus (IC) neurons receive glycinergic and GABAergic inputs, whereas inhibition in hippocampus (HC) predominantly relies on GABA. Astrocytes heterogeneously express neurotransmitter transporters and are expected to adapt to the local requirements regarding neurotransmitter homeostasis. Here we analyzed the expression of inhibitory neurotransmitter transporters in IC and HC astrocytes using whole-cell patch-clamp and single-cell reverse transcription-PCR. We show that most astrocytes in both regions expressed functional glycine transporters (GlyTs). Activation of these transporters resulted in an inward current (IGly) that was sensitive to the competitive GlyT1 agonist sarcosine. Astrocytes exhibited transcripts for GlyT1 but not for GlyT2. Glycine did not alter the membrane resistance (RM) arguing for the absence of functional glycine receptors (GlyRs). Thus, IGly was mainly mediated by GlyT1. Similarly, we found expression of functional GABA transporters (GATs) in all IC astrocytes and about half of the HC astrocytes. These transporters mediated an inward current (IGABA) that was sensitive to the competitive GAT-1 and GAT-3 antagonists NO711 and SNAP5114, respectively. Accordingly, transcripts for GAT-1 and GAT-3 were found but not for GAT-2 and BGT-1. Only in hippocampal astrocytes, GABA transiently reduced RM demonstrating the presence of GABAA receptors (GABAARs). However, IGABA was mainly not contaminated by GABAAR-mediated currents as RM changes vanished shortly after GABA application. In both regions, IGABA was stronger than IGly. Furthermore, in HC the IGABA/IGly ratio was larger compared to IC. Taken together, our results demonstrate that astrocytes are heterogeneous across and within distinct brain areas. Furthermore, we could show that the capacity for glycine and GABA uptake varies between both brain regions.
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Affiliation(s)
- Elsa Ghirardini
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.,Department of Medical Biotechnology and Translational Medicine, University of Milan, via Vanvitelli 32, I-20129, Milan, Italy.,Pharmacology and Brain Pathology Lab, Humanitas Clinical and Research Center, via Manzoni 56, I-20089, Rozzano, Italy
| | - Simon L Wadle
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Vanessa Augustin
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Jasmin Becker
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Sina Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Julia Hammerich
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany
| | - Jonathan Stephan
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.
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28
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Affiliation(s)
- Christopher L. Cioffi
- Departments of Basic and Clinical Sciences and Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences , Albany, NY, USA
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Söderpalm B, Lidö HH, Ericson M. The Glycine Receptor-A Functionally Important Primary Brain Target of Ethanol. Alcohol Clin Exp Res 2017; 41:1816-1830. [PMID: 28833225 DOI: 10.1111/acer.13483] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 08/15/2017] [Indexed: 12/27/2022]
Abstract
Identification of ethanol's (EtOH) primary molecular brain targets and determination of their functional role is an ongoing, important quest. Pentameric ligand-gated ion channels, that is, the nicotinic acetylcholine receptor, the γ-aminobutyric acid type A receptor, the 5-hydroxytryptamine3 , and the glycine receptor (GlyR), are such targets. Here, aspects of the structure and function of these receptors and EtOH's interaction with them are briefly reviewed, with special emphasis on the GlyR and the importance of this receptor and its ligands for EtOH pharmacology. It is suggested that GlyRs are involved in (i) the dopamine-activating effect of EtOH, (ii) regulating EtOH intake, and (iii) the relapse preventing effect of acamprosate. Exploration of the GlyR subtypes involved and efforts to develop subtype specific agonists or antagonists may offer new pharmacotherapies for alcohol use disorders.
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Affiliation(s)
- Bo Söderpalm
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Helga H Lidö
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Mia Ericson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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30
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Cioffi CL. Modulation of Glycine-Mediated Spinal Neurotransmission for the Treatment of Chronic Pain. J Med Chem 2017; 61:2652-2679. [PMID: 28876062 DOI: 10.1021/acs.jmedchem.7b00956] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic pain constitutes a significant and expanding worldwide health crisis. Currently available analgesics poorly serve individuals suffering from chronic pain, and new therapeutic agents that are more effective, safer, and devoid of abuse liabilities are desperately needed. Among the myriad of cellular and molecular processes contributing to chronic pain, spinal disinhibition of pain signaling to higher cortical centers plays a critical role. Accumulating evidence shows that glycinergic inhibitory neurotransmission in the spinal cord dorsal horn gates nociceptive signaling, is essential in maintaining physiological pain sensitivity, and is diminished in pathological pain states. Thus, it is hypothesized that agents capable of enhancing glycinergic tone within the dorsal horn could obtund nociceptor signaling to the brain and serve as analgesics for persistent pain. This Perspective highlights the potential that pharmacotherapies capable of increasing inhibitory spinal glycinergic neurotransmission hold in providing new and transformative analgesic therapies for the treatment of chronic pain.
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Affiliation(s)
- Christopher L Cioffi
- Departments of Basic and Clinical Sciences and Pharmaceutical Sciences , Albany College of Pharmacy and Health Sciences , 106 New Scotland Avenue , Albany , New York 12208 United States
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31
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Villarejo-López L, Jiménez E, Bartolomé-Martín D, Zafra F, Lapunzina P, Aragón C, López-Corcuera B. P2X receptors up-regulate the cell-surface expression of the neuronal glycine transporter GlyT2. Neuropharmacology 2017; 125:99-116. [PMID: 28734869 DOI: 10.1016/j.neuropharm.2017.07.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 07/11/2017] [Accepted: 07/17/2017] [Indexed: 12/27/2022]
Abstract
Glycinergic inhibitory neurons of the spinal dorsal horn exert critical control over the conduction of nociceptive signals to higher brain areas. The neuronal glycine transporter 2 (GlyT2) is involved in the recycling of synaptic glycine from the inhibitory synaptic cleft and its activity modulates intra and extracellular glycine concentrations. In this report we show that the stimulation of P2X purinergic receptors with βγ-methylene adenosine 5'-triphosphate induces the up-regulation of GlyT2 transport activity by increasing total and plasma membrane expression and reducing transporter ubiquitination. We identified the receptor subtypes involved by combining pharmacological approaches, siRNA-mediated protein knockdown, and dorsal root ganglion cell enrichment in brainstem and spinal cord primary cultures. Up-regulation of GlyT2 required the combined stimulation of homomeric P2X3 and P2X2 receptors or heteromeric P2X2/3 receptors. We measured the spontaneous glycinergic currents, glycine release and GlyT2 uptake concurrently in response to P2X receptor agonists, and showed that the impact of P2X3 receptor activation on glycinergic neurotransmission involves the modulation of GlyT2 expression or activity. The recognized pro-nociceptive action of P2X3 receptors suggests that the fine-tuning of GlyT2 activity may have consequences in nociceptive signal conduction.
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Affiliation(s)
- Lucía Villarejo-López
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Esperanza Jiménez
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - David Bartolomé-Martín
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain
| | - Francisco Zafra
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Pablo Lapunzina
- Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; Instituto de Genética Médica y Molecular, IdiPAZ-Hospital Universitario La Paz, Universidad Autónoma de Madrid, Madrid 28046, Spain
| | - Carmen Aragón
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; IdiPAZ-Hospital Universitario La Paz, Madrid, Spain
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; IdiPAZ-Hospital Universitario La Paz, Madrid, Spain.
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32
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Acton D, Miles GB. Differential regulation of NMDA receptors by d-serine and glycine in mammalian spinal locomotor networks. J Neurophysiol 2017; 117:1877-1893. [PMID: 28202572 PMCID: PMC5411468 DOI: 10.1152/jn.00810.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/11/2017] [Accepted: 02/11/2017] [Indexed: 12/11/2022] Open
Abstract
We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals. Activation of N-methyl-d-aspartate receptors (NMDARs) requires the binding of a coagonist, either d-serine or glycine, in addition to glutamate. Changes in occupancy of the coagonist binding site are proposed to modulate neural networks including those controlling swimming in frog tadpoles. Here, we characterize regulation of the NMDAR coagonist binding site in mammalian spinal locomotor networks. Blockade of NMDARs by d(−)-2-amino-5-phosphonopentanoic acid (d-APV) or 5,7-dichlorokynurenic acid reduced the frequency and amplitude of pharmacologically induced locomotor-related activity recorded from the ventral roots of spinal-cord preparations from neonatal mice. Furthermore, d-APV abolished synchronous activity induced by blockade of inhibitory transmission. These results demonstrate an important role for NMDARs in murine locomotor networks. Bath-applied d-serine enhanced the frequency of locomotor-related but not disinhibited bursting, indicating that coagonist binding sites are saturated during the latter but not the former mode of activity. Depletion of endogenous d-serine by d-amino acid oxidase or the serine-racemase inhibitor erythro-β-hydroxy-l-aspartic acid (HOAsp) increased the frequency of locomotor-related activity, whereas application of l-serine to enhance endogenous d-serine synthesis reduced burst frequency, suggesting a requirement for d-serine at a subset of synapses onto inhibitory interneurons. Consistent with this, HOAsp was ineffective during disinhibited activity. Bath-applied glycine (1–100 µM) failed to alter locomotor-related activity, whereas ALX 5407, a selective inhibitor of glycine transporter-1 (GlyT1), enhanced burst frequency, supporting a role for GlyT1 in NMDAR regulation. Together these findings indicate activity-dependent and synapse-specific regulation of the coagonist binding site within spinal locomotor networks, illustrating the importance of NMDAR regulation in shaping motor output. NEW & NOTEWORTHY We provide evidence that NMDARs within murine spinal locomotor networks determine the frequency and amplitude of ongoing locomotor-related activity in vitro and that NMDARs are regulated by d-serine and glycine in a synapse-specific and activity-dependent manner. In addition, glycine transporter-1 is shown to be an important regulator of NMDARs during locomotor-related activity. These results show how excitatory transmission can be tuned to diversify the output repertoire of spinal locomotor networks in mammals.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom
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33
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Glycinergic transmission: glycine transporter GlyT2 in neuronal pathologies. Neuronal Signal 2016; 1:NS20160009. [PMID: 32714574 PMCID: PMC7377260 DOI: 10.1042/ns20160009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 11/04/2016] [Accepted: 11/09/2016] [Indexed: 11/17/2022] Open
Abstract
Glycinergic neurons are major contributors to the regulation of neuronal excitability, mainly in caudal areas of the nervous system. These neurons control fluxes of sensory information between the periphery and the CNS and diverse motor activities like locomotion, respiration or vocalization. The phenotype of a glycinergic neuron is determined by the expression of at least two proteins: GlyT2, a plasma membrane transporter of glycine, and VIAAT, a vesicular transporter shared by glycine and GABA. In this article, we review recent advances in understanding the role of GlyT2 in the pathophysiology of inhibitory glycinergic neurotransmission. GlyT2 mutations are associated to decreased glycinergic function that results in a rare movement disease termed hyperekplexia (HPX) or startle disease. In addition, glycinergic neurons control pain transmission in the dorsal spinal cord and their function is reduced in chronic pain states. A moderate inhibition of GlyT2 may potentiate glycinergic inhibition and constitutes an attractive target for pharmacological intervention against these devastating conditions.
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34
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Imlach WL. New approaches to target glycinergic neurotransmission for the treatment of chronic pain. Pharmacol Res 2016; 116:93-99. [PMID: 27988386 DOI: 10.1016/j.phrs.2016.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/13/2016] [Accepted: 12/13/2016] [Indexed: 01/08/2023]
Abstract
Inhibitory glycinergic neurotransmission in the spinal cord dorsal horn plays an important role in regulating nociceptive signalling by inhibiting neuronal excitation. Blocking glycinergic transmission in the dorsal horn causes normally innocuous stimuli to become painful (allodynia) and increases sensitivity to noxious stimuli (hyperalgesia). Loss of inhibitory signalling is thought to contribute to the development of pathological pain. Management of neuropathic pain with current therapeutics is challenging and there is a great need for more effective treatments. Preclinical studies using drugs that increase glycinergic signalling by potentiating glycine receptor activity or inhibiting transporter activity suggest that targeting this system is a good therapeutic strategy. The spatially restricted expression of glycine receptors and transporters is an advantage for targeting specific pathologies such as pain. However, until recently there have been few pharmacological modulators identified and most of which do not specifically target glycinergic signalling. This mini-review provides an overview of recent advances in the development of therapeutics and novel approaches that aim to increase glycinergic neurotransmission for the treatment of persistent pain.
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Affiliation(s)
- Wendy L Imlach
- Discipline of Pharmacology, School of Medical Sciences, Rm. W300, Blackburn D06, The University of Sydney, Sydney NSW 2006, Australia.
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35
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Yue JTY, Abraham MA, Bauer PV, LaPierre MP, Wang P, Duca FA, Filippi BM, Chan O, Lam TKT. Inhibition of glycine transporter-1 in the dorsal vagal complex improves metabolic homeostasis in diabetes and obesity. Nat Commun 2016; 7:13501. [PMID: 27874011 PMCID: PMC5121412 DOI: 10.1038/ncomms13501] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/10/2016] [Indexed: 12/14/2022] Open
Abstract
Impaired glucose homeostasis and energy balance are integral to the pathophysiology of diabetes and obesity. Here we show that administration of a glycine transporter 1 (GlyT1) inhibitor, or molecular GlyT1 knockdown, in the dorsal vagal complex (DVC) suppresses glucose production, increases glucose tolerance and reduces food intake and body weight gain in healthy, obese and diabetic rats. These findings provide proof of concept that GlyT1 inhibition in the brain improves glucose and energy homeostasis. Considering the clinical safety and efficacy of GlyT1 inhibitors in raising glycine levels in clinical trials for schizophrenia, we propose that GlyT1 inhibitors have the potential to be repurposed as a treatment of both obesity and diabetes.
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Affiliation(s)
- Jessica T Y Yue
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7
| | - Mona A Abraham
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7.,Departments of Physiology, Toronto, Ontario, Canada M5S 1A8
| | - Paige V Bauer
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7.,Departments of Physiology, Toronto, Ontario, Canada M5S 1A8
| | - Mary P LaPierre
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7.,Departments of Physiology, Toronto, Ontario, Canada M5S 1A8
| | - Peili Wang
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Frank A Duca
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7
| | - Beatrice M Filippi
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7
| | - Owen Chan
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Tony K T Lam
- Toronto General Hospital Research Institute and Department of Medicine, UHN, Toronto, Ontario, Canada M5G 1L7.,Departments of Physiology, Toronto, Ontario, Canada M5S 1A8.,Departments of Medicine, University of Toronto, Toronto, Ontario, Canada M5S 1A8.,Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada M5G 2C4
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36
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Romei C, Bonifacino T, Milanese M, Usai C, Raiteri L. Colocalization of neurotransmitter transporters on the plasma membrane of the same nerve terminal may reflect cotransmission. Brain Res Bull 2016; 127:100-110. [DOI: 10.1016/j.brainresbull.2016.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/22/2016] [Accepted: 08/22/2016] [Indexed: 12/24/2022]
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37
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Advances in understanding the functions of native GlyT1 and GlyT2 neuronal glycine transporters. Neurochem Int 2016; 99:169-177. [DOI: 10.1016/j.neuint.2016.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/05/2016] [Accepted: 07/05/2016] [Indexed: 11/20/2022]
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38
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Cioffi CL, Liu S, Wolf MA, Guzzo PR, Sadalapure K, Parthasarathy V, Loong DTJ, Maeng JH, Carulli E, Fang X, Karunakaran K, Matta L, Choo SH, Panduga S, Buckle RN, Davis RN, Sakwa SA, Gupta P, Sargent BJ, Moore NA, Luche MM, Carr GJ, Khmelnitsky YL, Ismail J, Chung M, Bai M, Leong WY, Sachdev N, Swaminathan S, Mhyre AJ. Synthesis and Biological Evaluation of N-((1-(4-(Sulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide Inhibitors of Glycine Transporter-1. J Med Chem 2016; 59:8473-94. [PMID: 27559615 DOI: 10.1021/acs.jmedchem.6b00914] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We previously disclosed the discovery of rationally designed N-((1-(4-(propylsulfonyl)piperazin-1-yl)cycloalkyl)methyl)benzamide inhibitors of glycine transporter-1 (GlyT-1), represented by analogues 10 and 11. We describe herein further structure-activity relationship exploration of this series via an optimization strategy that primarily focused on the sulfonamide and benzamide appendages of the scaffold. These efforts led to the identification of advanced leads possessing a desirable balance of excellent in vitro GlyT-1 potency and selectivity, favorable ADME and in vitro pharmacological profiles, and suitable pharmacokinetic and safety characteristics. Representative analogue (+)-67 exhibited robust in vivo activity in the cerebral spinal fluid glycine biomarker model in both rodents and nonhuman primates. Furthermore, rodent microdialysis experiments also demonstrated that oral administration of (+)-67 significantly elevated extracellular glycine levels within the medial prefrontal cortex (mPFC).
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Affiliation(s)
- Christopher L Cioffi
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Shuang Liu
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Mark A Wolf
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Peter R Guzzo
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Kashinath Sadalapure
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Visweswaran Parthasarathy
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - David T J Loong
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Jun-Ho Maeng
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Edmund Carulli
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Xiao Fang
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Kalesh Karunakaran
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Lakshman Matta
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Sok Hui Choo
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Shailijia Panduga
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Ronald N Buckle
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Randall N Davis
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Samuel A Sakwa
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Priya Gupta
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Bruce J Sargent
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Nicholas A Moore
- Department of Medicinal Chemistry, AMRI , East Campus, 3 University Place, Rensselaer, New York 12144, United States
| | - Michele M Luche
- Bothell Research Center, AMRI , 22215 26th Ave SE, Bothell, Washington 98021-4425, United States
| | - Grant J Carr
- Bothell Research Center, AMRI , 22215 26th Ave SE, Bothell, Washington 98021-4425, United States
| | - Yuri L Khmelnitsky
- Drug Metabolism and Pharmacokinetics, AMRI , East Campus, 17 University Place, Rensselaer, New York 12144, United States
| | - Jiffry Ismail
- Drug Metabolism and Pharmacokinetics, AMRI , East Campus, 17 University Place, Rensselaer, New York 12144, United States
| | - Mark Chung
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Mei Bai
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Wei Yee Leong
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Nidhi Sachdev
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Srividya Swaminathan
- Discovery Research and Development Chemistry, Singapore Research Center, AMRI , 61 Science Park Road, Science Park III, 117525, Singapore
| | - Andrew J Mhyre
- Bothell Research Center, AMRI , 22215 26th Ave SE, Bothell, Washington 98021-4425, United States
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Hilinski WC, Bostrom JR, England SJ, Juárez-Morales JL, de Jager S, Armant O, Legradi J, Strähle U, Link BA, Lewis KE. Lmx1b is required for the glutamatergic fates of a subset of spinal cord neurons. Neural Dev 2016; 11:16. [PMID: 27553035 PMCID: PMC4995821 DOI: 10.1186/s13064-016-0070-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/08/2016] [Indexed: 01/27/2023] Open
Abstract
Background Alterations in neurotransmitter phenotypes of specific neurons can cause imbalances in excitation and inhibition in the central nervous system (CNS), leading to diseases. Therefore, the correct specification and maintenance of neurotransmitter phenotypes is vital. As with other neuronal properties, neurotransmitter phenotypes are often specified and maintained by particular transcription factors. However, the specific molecular mechanisms and transcription factors that regulate neurotransmitter phenotypes remain largely unknown. Methods In this paper we use single mutant, double mutant and transgenic zebrafish embryos to elucidate the functions of Lmx1ba and Lmx1bb in the regulation of spinal cord interneuron neurotransmitter phenotypes. Results We demonstrate that lmx1ba and lmx1bb are both expressed in zebrafish spinal cord and that lmx1bb is expressed by both V0v cells and dI5 cells. Our functional analyses demonstrate that these transcription factors are not required for neurotransmitter fate specification at early stages of development, but that in embryos with at least two lmx1ba and/or lmx1bb mutant alleles there is a reduced number of excitatory (glutamatergic) spinal interneurons at later stages of development. In contrast, there is no change in the numbers of V0v or dI5 cells. These data suggest that lmx1b-expressing spinal neurons still form normally, but at least a subset of them lose, or do not form, their normal excitatory fates. As the reduction in glutamatergic cells is only seen at later stages of development, Lmx1b is probably required either for the maintenance of glutamatergic fates or to specify glutamatergic phenotypes of a subset of later forming neurons. Using double labeling experiments, we also show that at least some of the cells that lose their normal glutamatergic phenotype are V0v cells. Finally, we also establish that Evx1 and Evx2, two transcription factors that are required for V0v cells to acquire their excitatory neurotransmitter phenotype, are also required for lmx1ba and lmx1bb expression in these cells, suggesting that Lmx1ba and Lmx1bb act downstream of Evx1 and Evx2 in V0v cells. Conclusions Lmx1ba and Lmx1bb function at least partially redundantly in the spinal cord and three functional lmx1b alleles are required in zebrafish for correct numbers of excitatory spinal interneurons at later developmental stages. Taken together, our data significantly enhance our understanding of how spinal cord neurotransmitter fates are regulated.
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Affiliation(s)
- William C Hilinski
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA.,Department of Neuroscience and Physiology, SUNY Upstate Medical University, 505 Irving Avenue, Syracuse, NY, 13210, USA
| | - Jonathan R Bostrom
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI, 53226, USA
| | - Samantha J England
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA
| | - José L Juárez-Morales
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA
| | - Sarah de Jager
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Olivier Armant
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021, Karlsruhe, Germany
| | - Jessica Legradi
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021, Karlsruhe, Germany
| | - Uwe Strähle
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021, Karlsruhe, Germany
| | - Brian A Link
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI, 53226, USA
| | - Katharine E Lewis
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA.
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40
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Asselot R, Simon-O'Brien E, Lebourgeois S, Nee G, Delaunay V, Duchatelle P, Bouet V, Dauphin F. Time-dependent impact of glutamatergic modulators on the promnesiant effect of 5-HT 6R blockade on mice recognition memory. Pharmacol Res 2016; 118:111-118. [PMID: 27373846 DOI: 10.1016/j.phrs.2016.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 01/19/2023]
Abstract
Selective antagonists at serotonin 5-HT6 receptors (5-HT6R) improve memory performance in rodents and are currently under clinical investigations. If blockade of 5-HT6R is known to increase glutamate release, only two studies have so far demonstrated an interaction between 5-HT6R and glutamate transmission, but both, using the non-competitive NMDA antagonist MK-801, insensitive to variations of glutamate concentrations. In a place recognition task, we investigated here in mice the role of glutamate transmission in the beneficial effects of 5-HT6R blockade (SB-271046). Through the use of increasing intervals (2, 4 and 6h) between acquisition and retrieval, we investigated the time-dependent impact of two different glutamatergic modulators. NMDAR-dependant glutamate transmission (NMDA Receptors) was either blocked by the competitive antagonist at NMDAR, CGS 19755, or potentiated by the glycine transporter type 1 (GlyT1) inhibitor, NFPS. Results showed that neither SB-271046, nor CGS 19755, nor NFPS, alter behavioural performances after short intervals, i.e. when control mice displayed significant memory performances (2h and 4h) (respectively 10, 3, and 0.625mg.kg-1). Conversely, with the 6h-interval, a situation in which spontaneous forgetting is observed in control mice, SB-271046 improved recognition memory performances. This beneficial effect was prevented when co-administered with either CGS 19755 or NFPS, which themselves had no effect. Interestingly, a dose-dependent effect was observed with NFPS, with promnesic effect observed at lower dose (0.156mg.kg-1) when administrated alone, whereas it did no modify promnesic effect of SB-271046. These results demonstrate that promnesiant effect induced by 5-HT6R blockade is sensitive to the competitive blockade of NMDAR and underline the need of a fine adjustment of the inhibition of GlyT1. Overall, our findings support the idea of a complex crosstalk between serotonergic and glutamatergic systems in the promnesic properties of 5-HT6R antagonists.
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Affiliation(s)
| | | | | | - Gérald Nee
- Normandie Univ, UNICAEN,GMPc, 14000 Caen, France
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Talele TT. The "Cyclopropyl Fragment" is a Versatile Player that Frequently Appears in Preclinical/Clinical Drug Molecules. J Med Chem 2016; 59:8712-8756. [PMID: 27299736 DOI: 10.1021/acs.jmedchem.6b00472] [Citation(s) in RCA: 565] [Impact Index Per Article: 70.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Recently, there has been an increasing use of the cyclopropyl ring in drug development to transition drug candidates from the preclinical to clinical stage. Important features of the cyclopropane ring are, the (1) coplanarity of the three carbon atoms, (2) relatively shorter (1.51 Å) C-C bonds, (3) enhanced π-character of C-C bonds, and (4) C-H bonds are shorter and stronger than those in alkanes. The present review will focus on the contributions that a cyclopropyl ring makes to the properties of drugs containing it. Consequently, the cyclopropyl ring addresses multiple roadblocks that can occur during drug discovery such as (a) enhancing potency, (b) reducing off-target effects,
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Affiliation(s)
- Tanaji T Talele
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University , 8000 Utopia Parkway, Queens, New York 11439, United States
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42
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Ultimate Translation: Developing Therapeutics Targeting on N-Methyl-d-Aspartate Receptor. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 76:257-309. [PMID: 27288080 DOI: 10.1016/bs.apha.2016.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
N-Methyl-d-aspartate receptors (NMDARs) are broadly distributed in the central nervous system (CNS), where they mediate excitatory signaling. NMDAR-mediated neurotransmission (NMDARMN) is the molecular engine of learning, memory and cognition, which are the basis for high cortical function. NMDARMN is also critically involved in the development and plasticity of CNS. Due to its essential and critical role, either over- or under-activation of NMDARMN can contribute substantially to the development of CNS disorders. The involvement of NMDARMN has been demonstrated in a variety of CNS disorders, including schizophrenia, depression, posttraumatic stress disorder, aging, mild cognitive impairment and Alzheimer's dementia, amyotrophic lateral sclerosis, and anti-NMDAR encephalitis. Several targets to "correct" or "reset" the NMDARMN in these CNS disorders have been identified and confirmed. With analogy to aminergic treatments, these targets include the glycine/d-serine co-agonist site, channel ionophore, glycine transporter-1, and d-amino acid oxidase. It is still early days in terms of developing novel therapeutics targeting the NMDAR. However, agents modulating NMDARMN hold promise as the next generation of CNS therapeutics.
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Barrow P, Parrott N, Alberati D, Paehler A, Koerner A. Preclinical Reproductive and Developmental Toxicity Profile of a Glycine Transporter Type 1 (Glyt1) Inhibitor. ACTA ACUST UNITED AC 2016; 107:148-56. [DOI: 10.1002/bdrb.21179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/12/2016] [Indexed: 01/12/2023]
Affiliation(s)
- Paul Barrow
- Roche Pharmaceutical Research and Early Development; F. Hoffmann-La-Roche; Basel Switzerland
| | - Neil Parrott
- Roche Pharmaceutical Research and Early Development; F. Hoffmann-La-Roche; Basel Switzerland
| | - Daniela Alberati
- Roche Pharmaceutical Research and Early Development; F. Hoffmann-La-Roche; Basel Switzerland
| | - Axel Paehler
- Roche Pharmaceutical Research and Early Development; F. Hoffmann-La-Roche; Basel Switzerland
| | - Annette Koerner
- Roche Pharmaceutical Research and Early Development; F. Hoffmann-La-Roche; Basel Switzerland
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44
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The NMDA Receptor and Schizophrenia: From Pathophysiology to Treatment. ADVANCES IN PHARMACOLOGY 2016; 76:351-82. [PMID: 27288082 DOI: 10.1016/bs.apha.2016.01.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Schizophrenia is a severe mental illness that affects almost 1% of the population worldwide. Even though the etiology of schizophrenia is uncertain, it is believed to be a neurodevelopmental disorder that results from a combination of environmental insults and genetic vulnerabilities. Over the past 20 years, there has been a confluence of evidence from many research disciplines pointing to alterations in excitatory signaling, particularly involving hypofunction of the N-methyl-d-aspartate receptor (NMDAR), as a key contributor to the schizophrenia disease process. This review describes the structure-function relationship of the NMDAR channel and how the glycine modulatory site acts as an important regulator of its activity. In addition, this review highlights the genetic, pharmacologic, and biochemical evidence supporting the hypothesis that NMDAR hypofunction contributes to the pathophysiology of schizophrenia. Finally, this chapter highlights some of the most recent and promising pharmacological strategies that are designed to either, directly or indirectly, augment NMDAR function in an effort to treat the cognitive and negative symptoms of schizophrenia that are not helped by currently available medications.
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45
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Glycine transporter2 inhibitors: Getting the balance right. Neurochem Int 2015; 98:89-93. [PMID: 26723543 DOI: 10.1016/j.neuint.2015.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/13/2015] [Accepted: 12/18/2015] [Indexed: 12/28/2022]
Abstract
Neurotransmitter transporters are targets for a wide range of therapeutically useful drugs. This is because they have the capacity to selectively manipulate the dynamics of neurotransmitter concentrations and thereby enhance or diminish signalling through particular brain pathways. High affinity glycine transporters (GlyTs) regulate extracellular concentrations of glycine and provide novel therapeutic targets for neurological disorders.
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Ogawa T, Ishizuka O, Ueda T, Tyagi P, Chancellor MB, Yoshimura N. Current and emerging drugs for interstitial cystitis/bladder pain syndrome (IC/BPS). Expert Opin Emerg Drugs 2015; 20:555-70. [DOI: 10.1517/14728214.2015.1105216] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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47
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Raiteri L, Raiteri M. Multiple functions of neuronal plasma membrane neurotransmitter transporters. Prog Neurobiol 2015; 134:1-16. [PMID: 26300320 DOI: 10.1016/j.pneurobio.2015.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/09/2015] [Accepted: 08/18/2015] [Indexed: 12/11/2022]
Abstract
Removal from receptors of neurotransmitters just released into synapses is one of the major steps in neurotransmission. Transporters situated on the plasma membrane of nerve endings and glial cells perform the process of neurotransmitter (re)uptake. Because the density of transporters in the membranes can fluctuate, transporters can determine the transmitter concentrations at receptors, thus modulating indirectly the excitability of neighboring neurons. Evidence is accumulating that neurotransmitter transporters can exhibit multiple functions. Being bidirectional, neurotransmitter transporters can mediate transmitter release by working in reverse, most often under pathological conditions that cause ionic gradient dysregulations. Some transporters reverse to release transmitters, like dopamine or serotonin, when activated by 'indirectly acting' substrates, like the amphetamines. Some transporters exhibit as one major function the ability to capture transmitters into nerve terminals that perform insufficient synthesis. Transporter activation can generate conductances that regulate directly neuronal excitability. Synaptic and non-synaptic transporters play different roles. Cytosolic Na(+) elevations accompanying transport can interact with plasmalemmal or/and mitochondrial Na(+)/Ca(2+) exchangers thus generating calcium signals. Finally, neurotransmitter transporters can behave as receptors mediating releasing stimuli able to cause transmitter efflux through multiple mechanisms. Neurotransmitter transporters are therefore likely to play hitherto unknown roles in multiple therapeutic treatments.
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Affiliation(s)
- Luca Raiteri
- Department of Pharmacy, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy; National Institute of Neuroscience, Genoa, Italy
| | - Maurizio Raiteri
- Department of Pharmacy, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy; National Institute of Neuroscience, Genoa, Italy.
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48
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Mothet JP, Le Bail M, Billard JM. Time and space profiling of NMDA receptor co-agonist functions. J Neurochem 2015; 135:210-25. [DOI: 10.1111/jnc.13204] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/12/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Affiliation(s)
- Jean-Pierre Mothet
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Matildé Le Bail
- Team ‘Gliotransmission and Synaptopathies’; Aix-Marseille Université; CNRS; CRN2M UMR7286; Marseille France
| | - Jean-Marie Billard
- Center of Psychiatry and Neuroscience; University Paris Descartes; Sorbonne Paris City; UMR 894; Paris France
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Schlösser L, Barthel F, Brandenburger T, Neumann E, Bauer I, Eulenburg V, Werdehausen R, Hermanns H. Glycine transporter GlyT1, but not GlyT2, is expressed in rat dorsal root ganglion--Possible implications for neuropathic pain. Neurosci Lett 2015; 600:213-9. [PMID: 26101830 DOI: 10.1016/j.neulet.2015.06.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/11/2015] [Accepted: 06/12/2015] [Indexed: 12/23/2022]
Abstract
Glycinergic inhibitory neurotransmission plays a pivotal role in the development of neuropathic pain. The glycine concentration in the synaptic cleft is controlled by the glycine transporters GlyT1 and GlyT2. GlyT1 is expressed throughout the central nervous system, while GlyT2 is exclusively located in glycinergic neurons. Aim of the present study was to investigate whether GlyTs are also expressed in the peripheral sensory nervous system and whether their expression is modulated in experimental neuropathic pain. Neuropathic pain was induced in male Wistar rats by Chronic Constriction Injury (CCI) and verified by assessment of mechanical allodynia (von Frey method). Expression patterns of GlyTs and the glycine binding subunit NR1 of the N-methyl-d-aspartate (NMDA) receptor in the spinal cord and dorsal root ganglia (DRG) were analyzed by Western blot analysis, PCR and immunohistochemistry. While both GlyT1 and GlyT2 were detected in the spinal cord, only GlyT1, but not GlyT2, was detected in DRG. Immunofluorescence revealed a strictly neuronal localization of GlyT1 and a co-localization of GlyT1 and NR1 in DRG. Compared to sham procedure, spinal cord and DRG expression of GlyT1 was not altered and NR1 was unchanged in DRG 12 days after CCI. GlyT1, but not GlyT2, is expressed in the peripheral sensory nervous system. The co-expression of GlyT1 and NMDA receptors in DRG suggests that GlyT1 regulates glycine concentration at the glycine binding site of the NMDA receptor. Differential regulation of GlyT1 expression in the spinal cord or DRG, however, does not seem to be associated with the development of neuropathic pain.
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Affiliation(s)
- Lukas Schlösser
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Franziska Barthel
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Timo Brandenburger
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Elena Neumann
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Inge Bauer
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Volker Eulenburg
- Institute of Biochemistry, Emil-Fischer-Center, University of Erlangen-Nürnberg, Fahrstrasse 17, 91054 Erlangen, Germany
| | - Robert Werdehausen
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Henning Hermanns
- Department of Anesthesiology, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany; Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1100 DD Amsterdam, The Netherlands.
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50
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Yoshimura N, Oguchi T, Yokoyama H, Funahashi Y, Yoshikawa S, Sugino Y, Kawamorita N, Kashyap MP, Chancellor MB, Tyagi P, Ogawa T. Bladder afferent hyperexcitability in bladder pain syndrome/interstitial cystitis. Int J Urol 2015; 21 Suppl 1:18-25. [PMID: 24807488 DOI: 10.1111/iju.12308] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 08/27/2013] [Indexed: 12/30/2022]
Abstract
Bladder pain syndrome/interstitial cystitis is a disease with lower urinary tract symptoms, such as bladder pain and urinary frequency, which results in seriously impaired quality of life of patients. The extreme pain and urinary frequency are often difficult to treat. Although the etiology of bladder pain syndrome/interstitial cystitis is still not known, there is increasing evidence showing that afferent hyperexcitability as a result of neurogenic bladder inflammation and urothelial dysfunction is important to the pathophysiological basis of symptom development. Further investigation of the pathophysiology will lead to the effective treatment of patients with bladder pain syndrome/interstitial cystitis.
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Affiliation(s)
- Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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