1
|
Orzylowski M, Fujiwara E, Mousseau DD, Baker GB. An Overview of the Involvement of D-Serine in Cognitive Impairment in Normal Aging and Dementia. Front Psychiatry 2021; 12:754032. [PMID: 34707525 PMCID: PMC8542907 DOI: 10.3389/fpsyt.2021.754032] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/02/2021] [Indexed: 12/14/2022] Open
Abstract
Dementia, of which Alzheimer's disease (AD) is the most common form, is characterized by progressive cognitive deterioration, including profound memory loss, which affects functioning in many aspects of life. Although cognitive deterioration is relatively common in aging and aging is a risk factor for AD, the condition is not necessarily a part of the aging process. The N-methyl-D-aspartate glutamate receptor (NMDAR) and its co-agonist D-serine are currently of great interest as potential important contributors to cognitive function in normal aging and dementia. D-Serine is necessary for activation of the NMDAR and in maintenance of long-term potentiation (LTP) and is involved in brain development, neuronal connectivity, synaptic plasticity and regulation of learning and memory. In this paper, we review evidence, from both preclinical and human studies, on the involvement of D-serine (and the enzymes involved in its metabolism) in regulation of cognition. Potential mechanisms of action of D-serine are discussed in the context of normal aging and in dementia, as is the potential for using D-serine as a potential biomarker and/or therapeutic agent in dementia. Although there is some controversy in the literature, it has been proposed that in normal aging there is decreased expression of serine racemase and decreased levels of D-serine and down-regulation of NMDARs, resulting in impaired synaptic plasticity and deficits in learning and memory. In contrast, in AD there appears to be activation of serine racemase, increased levels of D-serine and overstimulation of NMDARs, resulting in cytotoxicity, synaptic deficits, and dementia.
Collapse
Affiliation(s)
- Magdalena Orzylowski
- Villa Caritas Geriatric Psychiatry Hospital, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Esther Fujiwara
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Darrell D Mousseau
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Glen B Baker
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
2
|
Zhang X, Zhang R, Chen J, Wu J. Neuroprotective effects of DAAO are mediated via the ERK1/2 signaling pathway in a glaucomatous animal model. Exp Eye Res 2020; 190:107892. [DOI: 10.1016/j.exer.2019.107892] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/31/2019] [Accepted: 12/03/2019] [Indexed: 01/06/2023]
|
3
|
Blandford SN, Hooper ML, Yabana T, Chauhan BC, Baldridge WH, Farrell SRM. Retinal Characterization of the Thy1-GCaMP3 Transgenic Mouse Line After Optic Nerve Transection. Invest Ophthalmol Vis Sci 2019; 60:183-191. [PMID: 30640971 DOI: 10.1167/iovs.18-25861] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose GCaMP3 is a genetically encoded calcium indicator for monitoring intracellular calcium dynamics. We characterized the expression pattern and functional properties of GCaMP3 in the Thy1-GCaMP3 transgenic mouse retina. Methods To determine the specificity of GCaMP3 expression, Thy1-GCaMP3 (B6; CBA-Tg(Thy1-GCaMP3)6Gfng/J) retinas were processed for immunohistochemistry with anti-green fluorescent protein (anti-GFP, to enhance GCaMP3 fluorescence), anti-RBPMS (retinal ganglion cell [RGC]-specific marker), and antibodies against amacrine cell markers (ChAT, GABA, GAD67, syntaxin). Calcium imaging was used to characterize functional responses of GCaMP3-expressing (GCaMP+) cells by recording calcium transients evoked by superfusion of kainic acid (KA; 10, 50, or 100 μM). In a subset of animals, optic nerve transection (ONT) was performed 3, 5, or 7 days prior to calcium imaging. Results GFP immunoreactivity colocalized with RBPMS but not amacrine cell markers in both ONT and non-ONT (control) groups. Calcium transients evoked by KA were reduced after ONT (50 μM KA; ΔF/F0 [SD]; control: 1.00 [0.67], day 3: 0.50 [0.35], day 5: 0.31 [0.28], day 7: 0.35 [0.36]; P < 0.05 versus control). There was also a decrease in the number of GCaMP3+ cells after ONT (cells/mm2 [SD]; control: 2198 [453], day 3: 2224 [643], day 5: 1383 [375], day 7: 913 [178]; P < 0.05). Furthermore, the proportion of GCaMP3+ cells that responded to KA decreased after ONT (50 μM KA, 97%, 54%, 47%, and 58%; control, 3, 5, and 7 days, respectively). Conclusions Following ONT, functional RGC responses are lost prior to the loss of RGC somata, suggesting that anatomical markers of RGCs may underestimate the extent of RGC dysfunction.
Collapse
Affiliation(s)
- Stephanie N Blandford
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.,Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Michele L Hooper
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Takeshi Yabana
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.,Tohoku University Graduate School of Medicine, Department of Ophthalmology, Sendai, Japan
| | - Balwantray C Chauhan
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.,Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.,Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
| | - William H Baldridge
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.,Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Spring R M Farrell
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.,Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada.,Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
| |
Collapse
|
4
|
Zhang X, Zhang R, Zhou X, Wu J. Decreased d-Serine Levels Prevent Retinal Ganglion Cell Apoptosis in a Glaucomatous Animal Model. Invest Ophthalmol Vis Sci 2019; 59:5045-5052. [PMID: 30357398 DOI: 10.1167/iovs.18-24691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to determine d-Serine and d-Serine synthetase serine racemase (SR) expression and whether decreased d-Serine expression has protective effects on retinal ganglion cells (RGCs) in a glaucomatous animal model. Methods The rat chronic intraocular hypertension (COH) model was generated as a glaucomatous animal model by cauterizing three episcleral veins. Quantitative analysis of RGC survival was determined by the counting of retrograde FluoroGold-labeled RGCs. The level of d-Serine in the retinas and aqueous humor was determined by Ultra High Performance Liquid Chromatography coupled to triple-quadrupole Mass Spectrometry (UHPLC-MS/MS). Retinal expression of serine racemase (SR) protein was determined by immunohistochemistry and Western blot analysis. The TUNEL assay was used to detect cell apoptosis. Results The content of d-Serine increased significantly in the glaucomatous retina of the COH model 2 weeks after surgery compared with the control retina. d-Serine synthetase SR expression in the right glaucomatous eye increased slightly after surgery compared with that in the left control eye and remained at this high level for 6 weeks after surgery. SR-positive cells were located mainly in the ganglion cell layer (GCL) of the retina. d-Amino acid oxidase (DAAO) treatment significantly increased RGC survival in the glaucomatous eyes, and the TUNEL assay was used to confirm that DAAO reduced the number of TUNEL-positive cells in glaucomatous eyes. However, excess d-Serine could not exacerbate RGC loss in the COH model. Conclusions Increased d-Serine and SR expressions in the retina of the COH model were detected. DAAO treatment significantly increased RGC survival in the glaucomatous eyes. These results suggest that decreased d-Serine expression has protective effects on RGCs.
Collapse
Affiliation(s)
- Xuejin Zhang
- Eye & ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Rong Zhang
- Eye & ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xujiao Zhou
- Eye & ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jihong Wu
- Eye & ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University); Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| |
Collapse
|
5
|
Staubli U, Rangel-Diaz N, Alcantara M, Li YX, Yang JY, Zhang KM, Foster AC. Restoration of visual performance by d-serine in models of inner and outer retinal dysfunction assessed using sweep VEP measurements in the conscious rat and rabbit. Vision Res 2016; 127:35-48. [PMID: 27461280 DOI: 10.1016/j.visres.2016.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 07/12/2016] [Accepted: 07/12/2016] [Indexed: 10/21/2022]
Abstract
The NMDA subtype of glutamate receptor and its co-agonist d-serine play a key role in synaptic function in the central nervous system (CNS), including visual cortex and retina. In retinal diseases such as glaucoma and macular degeneration, a loss of vision arises from malfunction of retinal cells, resulting in a glutamate hypofunctional state along the visual pathway in the affected parts of the visual field. An effective strategy to remedy this loss of function might be to increase extracellular levels of d-serine and thereby boost synaptic NMDA receptor-mediated visual transmission and/or plasticity to compensate for the impairment. We tested this idea in brain slices of visual cortex exhibiting long-term potentiation, and in rodent models of visual dysfunction caused by retinal insults at a time when the injury had stabilized to look for neuroenhancement effects. An essential aspect of the in vivo studies involved adapting sweep VEP technology to conscious rats and rabbits and combining it with intracortical recording while the animals were actively attending to visual information. Using this technology allowed us to establish complete contrast sensitivity function curves. We found that systemic d-serine dose-dependently rescued the contrast sensitivity impairment in rats with blue light-induced visual dysfunction. In rabbits with inner retinal dysfunction, both systemic and intravitreal routes of d-serine provided a rescue of visual function. In sum, we show that co-agonist stimulation of the NMDA receptor via administration of exogenous d-serine might be an effective therapeutic strategy to enhance visual performance and compensate for the loss of vision resulting from retinal disease.
Collapse
Affiliation(s)
- Ursula Staubli
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Natalie Rangel-Diaz
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Miguel Alcantara
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Yong-Xin Li
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA.
| | - Jia-Ying Yang
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Kai-Ming Zhang
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Alan C Foster
- Department of Biological Sciences, Allergan Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| |
Collapse
|
6
|
The Effect of Glutamate Receptor Agonists on Mouse Retinal Astrocyte [Ca(2+)]i. BIOMED RESEARCH INTERNATIONAL 2016; 2016:8178162. [PMID: 27413752 PMCID: PMC4930813 DOI: 10.1155/2016/8178162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/18/2016] [Accepted: 05/22/2016] [Indexed: 11/21/2022]
Abstract
Calcium-imaging techniques were used to determine if mouse retinal astrocytes in situ respond to agonists of ionotropic (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA; N-methyl-D-aspartate, NMDA) and metabotropic (S-3,5-dihydroxyphenylglycine, DHPG; trans-1-amino-1,3-cyclopentanedicarboxylic acid, ACPD) glutamate receptors. In most cases we found no evidence that retinal astrocyte intracellular calcium ion concentration ([Ca2+]i) increased in response to these glutamate agonists. The one exception was AMPA that increased [Ca2+]i in some, but not all, mouse retinal astrocytes in situ. However, AMPA did not increase [Ca2+]i in mouse retinal astrocytes in vitro, suggesting that the effect of AMPA in situ may be indirect.
Collapse
|
7
|
Riebe I, Seth H, Culley G, Dósa Z, Radi S, Strand K, Fröjd V, Hanse E. Tonically active NMDA receptors--a signalling mechanism critical for interneuronal excitability in the CA1 stratum radiatum. Eur J Neurosci 2015; 43:169-78. [PMID: 26547631 DOI: 10.1111/ejn.13128] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 11/02/2015] [Accepted: 11/03/2015] [Indexed: 11/30/2022]
Abstract
In contrast to tonic extrasynaptic γ-aminobutyric acid (GABA)A receptor-mediated signalling, the physiological significance of tonic extrasynaptic N-methyl-D-aspartate (NMDA) receptor (NMDAR)-mediated signalling remains uncertain. In this study, reversible open-channel blockers of NMDARs, memantine and phencyclidine (PCP) were used as tools to examine tonic NMDAR-mediated signalling in rat hippocampal slices. Memantine in concentrations up to 10 μM had no effect on synaptically evoked NMDAR-mediated responses in pyramidal neurons or GABAergic interneurons. On the other hand, 10 μM memantine reduced tonic NMDAR-mediated currents in GABAergic interneurons by approximately 50%. These tonic NMDAR-mediated currents in interneurons contributed significantly to the excitability of the interneurons as 10 μM memantine reduced the disynaptic inhibitory postsynaptic current in pyramidal cells by about 50%. Moreover, 10 μM memantine, but also PCP in concentrations ≤ 1 μM, increased the magnitude of the population spike, likely because of disinhibition. The relatively higher impact of tonic NMDAR-mediated signalling in interneurons was at least partly explained by the expression of GluN2D-containing NMDARs, which was not observed in mature pyramidal cells. The current results are consistent with the idea that low doses of readily reversible NMDAR open-channel blockers preferentially inhibit tonically active extrasynaptic NMDARs, and they suggest that tonically active NMDARs contribute more prominently to the intrinsic excitation in GABAergic interneurons than in pyramidal cells. It is proposed that this specific difference between interneurons and pyramidal cells can explain the disinhibition caused by the Alzheimer's disease medication memantine.
Collapse
Affiliation(s)
- Ilse Riebe
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Henrik Seth
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Georgia Culley
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Zita Dósa
- Synaptic Physiology Laboratory, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Shayma Radi
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Karin Strand
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Victoria Fröjd
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| | - Eric Hanse
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, Gothenburg University, Medicinaregatan 11, 405 30, Gothenburg, Sweden
| |
Collapse
|
8
|
Armagan G, Keser A, Atalayın Ç, Dagcı T. Tideglusib protects neural stem cells against NMDA receptor overactivation. Pharmacol Rep 2015; 67:823-31. [DOI: 10.1016/j.pharep.2015.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 01/12/2015] [Accepted: 01/13/2015] [Indexed: 11/28/2022]
|
9
|
Sargoy A, Barnes S, Brecha NC, Pérez De Sevilla Müller L. Immunohistochemical and calcium imaging methods in wholemount rat retina. J Vis Exp 2014:e51396. [PMID: 25349920 DOI: 10.3791/51396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
In this paper we describe the tools, reagents, and the practical steps that are needed for: 1) successful preparation of wholemount retinas for immunohistochemistry and, 2) calcium imaging for the study of voltage gated calcium channel (VGCC) mediated calcium signaling in retinal ganglion cells. The calcium imaging method we describe circumvents issues concerning non-specific loading of displaced amacrine cells in the ganglion cell layer.
Collapse
Affiliation(s)
- Allison Sargoy
- Department of Neurobiology, University of California, Los Angeles
| | - Steven Barnes
- Department of Neurobiology, University of California, Los Angeles; Veterans Administration Greater Los Angeles Healthcare System; Departments of Physiology & Biophysics and Ophthalmology & Visual Sciences, Dalhousie University
| | - Nicholas C Brecha
- Department of Neurobiology, University of California, Los Angeles; Veterans Administration Greater Los Angeles Healthcare System; Departments of Neurobiology and Medicine, Jules Stein Eye Institute, CURE-Digestive Diseases Research Center, David Geffen School of Medicine, University of California, Los Angeles
| | | |
Collapse
|
10
|
Rozsa E, Vigh J. Glycine transporter 1 modulates GABA release from amacrine cells by controlling occupancy of coagonist binding site of NMDA receptors. J Neurophysiol 2013; 110:1393-403. [PMID: 23803324 DOI: 10.1152/jn.00193.2013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The occupancy of coagonist binding sites of NMDA receptors (NMDARs) by glycine or d-serine has been thought to mediate NMDAR-dependent excitatory signaling, as simultaneous binding of glutamate and a coagonist is obligatory for NMDAR activation. Amacrine cells (ACs) mediating GABAergic feedback inhibition of mixed bipolar cells (Mbs) in the goldfish retina have been shown to express NMDARs. Here we studied whether NMDAR-mediated GABAergic inhibitory currents (IGABA) recorded from the axon terminals of Mbs are influenced by experimental manipulations altering retinal glycine and d-serine levels. Feedback IGABA in Mb axon terminals was triggered by focal NMDA application or by synaptically released glutamate from depolarized Mb terminals. In both cases, blocking the coagonist binding sites of NMDARs eliminated the NMDAR-dependent IGABA, demonstrating that coagonist binding is critical in mediating NMDAR activity-triggered GABA release. Glycine transporter 1 (GLYT1) inhibition increased IGABA, indicating that coagonist binding sites of NMDARs on ACs providing GABAergic feedback inhibition to Mbs were not saturated. Focal glycine application, in the presence of the ionotropic glycine receptor blocker strychnine, triggered a GLYT1-dependent current in ACs, suggesting that GLYT1 expressed by putative glycinergic ACs controls the saturation level of NMDARs' coagonist sites. External d-serine also increased NMDAR activation-triggered IGABA in Mbs, further substantiating that the coagonist sites were unsaturated. Together, our findings demonstrate that coagonist modulation of glutamatergic input to GABAergic ACs via NMDARs is strongly reflected in the AC neuronal output (i.e., transmitter release) and thus is critical in GABAergic signal transfer function in the inner retina.
Collapse
Affiliation(s)
- Eva Rozsa
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | | |
Collapse
|
11
|
Billard JM. d-Amino acids in brain neurotransmission and synaptic plasticity. Amino Acids 2012; 43:1851-60. [DOI: 10.1007/s00726-012-1346-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/16/2012] [Indexed: 01/25/2023]
|
12
|
Sullivan SJ, Miller RF. AMPA receptor-dependent, light-evoked D-serine release acts on retinal ganglion cell NMDA receptors. J Neurophysiol 2012; 108:1044-51. [PMID: 22592312 DOI: 10.1152/jn.00264.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
NMDA receptor (NMDAR) activation requires coincident binding of the excitatory neurotransmitter glutamate and a coagonist, either glycine or D-serine. Changes in NMDAR currents during neural transmission are typically attributed to glutamate release against a steady background of coagonist, excluding the possibility of coagonist release. AMPA receptor (AMPAR) stimulation evokes D-serine release, but it is unknown whether this is a physiological phenomenon capable of influencing synaptic responses. In this study, we utilized the intact retina to determine whether light-evoked synaptic activity in retinal ganglion cells (RGCs) is shaped by a dynamic pool of coagonist. The application of AMPAR antagonist abolished light-evoked NMDAR currents, which were rescued by adding coagonist to the bath. When NMDA was globally applied to RGCs via bath or picospritzing, the coagonist occupancy was also dependent on AMPARs but to a lesser extent than that observed during light responses, suggesting a difference in extrasynaptic coagonist regulation. By saturating the glutamate binding site of NMDARs, we were able to detect released coagonist reaching RGCs during light-evoked responses. Mutant mice lacking the d-serine-synthesizing enzyme serine racemase were deficient in coagonist release. Coagonist release in wild-type retinas was notably greater in ON than in OFF responses and depended on AMPARs. These findings suggest activity-dependent modulation of coagonist availability, particularly D-serine, and may add an extra dimension to NMDAR coincidence detection in the retina.
Collapse
Affiliation(s)
- Steve J Sullivan
- Univ. of Minnesota, Dept. of Neuroscience, Minneapolis, MN 55455, USA.
| | | |
Collapse
|
13
|
Daniels BA, Wood L, Tremblay F, Baldridge WH. Functional evidence for D-serine inhibition of non-N-methyl-D-aspartate ionotropic glutamate receptors in retinal neurons. Eur J Neurosci 2011; 35:56-65. [PMID: 22128843 DOI: 10.1111/j.1460-9568.2011.07925.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
D-Serine is an important signaling molecule throughout the central nervous system, acting as an N-methyl-D-aspartate (NMDA) receptor coagonist. This study investigated the D-serine modulation of non-NMDA ionotropic glutamate receptors expressed by inner retinal neurons. We first identified that the degradation of endogenous retinal D-serine, by application of D-amino acid oxidase, caused an enhancement of kainate- and α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptor-mediated calcium responses from the ganglion cell layer of the isolated rat retina and light-evoked responses obtained by multi-electrode array recordings from the guinea pig retina. Approximately 30-45% of cells were endogenously inhibited by D-serine, as suggested by the effect of D-amino acid oxidase. Conversely, bath application of D-serine caused a reduction in multi-electrode array recorded responses and decreased kainate, but not potassium-induced calcium responses, in a concentration-dependent manner (IC(50), 280 μm). Using cultured retinal ganglion cells to reduce network influences, D-serine reduced kainate-induced calcium responses and AMPA induced whole-cell currents. Finally, the inhibitory effect of D-serine on the kainate-induced calcium response was abolished by IEM 1460, thereby identifying calcium-permeable AMPA receptors as a potential target for D-serine. To our knowledge, this is the first study to address specifically the effect of D-serine on AMPA/kainate receptors in intact central nervous system tissue, to identify its effect on calcium permeable AMPA receptors and to report the endogenous inhibition of AMPA/kainate receptors.
Collapse
Affiliation(s)
- Bryan A Daniels
- Department of Anatomy and Neurobiology, Dalhousie University, Sir Charles Tupper Building, 5850 College Street, Halifax, NS, Canada B3H 4R2
| | | | | | | |
Collapse
|
14
|
Labrie V, Wong AHC, Roder JC. Contributions of the D-serine pathway to schizophrenia. Neuropharmacology 2011; 62:1484-503. [PMID: 21295046 DOI: 10.1016/j.neuropharm.2011.01.030] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 01/16/2011] [Accepted: 01/19/2011] [Indexed: 01/30/2023]
Abstract
The glutamate neurotransmitter system is one of the major candidate pathways for the pathophysiology of schizophrenia, and increased understanding of the pharmacology, molecular biology and biochemistry of this system may lead to novel treatments. Glutamatergic hypofunction, particularly at the NMDA receptor, has been hypothesized to underlie many of the symptoms of schizophrenia, including psychosis, negative symptoms and cognitive impairment. This review will focus on D-serine, a co-agonist at the NMDA receptor that in combination with glutamate, is required for full activation of this ion channel receptor. Evidence implicating D-serine, NMDA receptors and related molecules, such as D-amino acid oxidase (DAO), G72 and serine racemase (SRR), in the etiology or pathophysiology of schizophrenia is discussed, including knowledge gained from mouse models with altered D-serine pathway genes and from preliminary clinical trials with D-serine itself or compounds modulating the D-serine pathway. Abnormalities in D-serine availability may underlie glutamatergic dysfunction in schizophrenia, and the development of new treatments acting through the D-serine pathway may significantly improve outcomes for many schizophrenia patients.
Collapse
Affiliation(s)
- Viviane Labrie
- Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada.
| | | | | |
Collapse
|
15
|
Abstract
The N-methyl-D-aspartate receptor (NMDAR) co-agonist D-serine is important in a number of different processes in the CNS, ranging from synaptic plasticity to disease states, including schizophrenia. D-serine appears to be the major co-agonist acting on retinal ganglion cell NMDA receptors, but the cell type from which it originates and whether its release can be modulated by activity are unknown. In this study, we utilized a mutant mouse line with elevated d-serine to investigate this question. Direct measurements of extracellular D-serine using capillary electrophoresis demonstrate that D-serine can be released from the intact mouse retina through an α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptor (AMPAR) dependent mechanism. α-Amino-3-hydroxyl-5-methyl-4-isoxazole-propionate-evoked D-serine release persisted in the presence of a cocktail of neural inhibitors but was abolished after administration of a glial toxin. These findings provide the first evidence that extracellular D-serine levels in the retina can be modulated, and that such modulation is contingent upon glial cell activity.
Collapse
Affiliation(s)
- Steve J Sullivan
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.
| | | |
Collapse
|