Are there ionotropic glutamate receptors on the rod bipolar cell of the mouse retina?

1997 ◽  
Vol 14 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Thomas E. Hughes
Keyword(s):  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Bipolar Cell ◽  
Metabotropic Glutamate Receptor ◽  
Bipolar Cells ◽  
Ionotropic Glutamate Receptors ◽  
Mouse Retina ◽  
Rod Photoreceptor ◽  
Metabotropic Glutamate ◽  
C Terminus

AbstractThere is some evidence that the mammalian rod bipolar cell expresses ionotropic glutamate receptors. This is surprising in light of the strong evidence that the glutamate released by the rod photoreceptor acts upon a metabotropic glutamate receptor-mGluRo-present in the dendrites of the rod bipolar cell. To reexamine the issue of which glutamate receptor subunits may be present on the rod bipolar cell, an immunohistochemical study of acutely dissociated retinal cells was undertaken. Two monoclonal antibodies provided some evidence that GluR2 and/or GluR4, as well as NMDAR1 subunit, are present on the rod bipolar cell. A monoclonal antibody directed against the N-terminus of GluR2 labeled the rod bipolar cells, but two antisera directed against the C-terminus of the same subunit did not. One possible explanation for this discrepancy could be that the rare splice variant GluR2-long, which is endowed with a different C-terminus, could be expressed by the rod bipolar cell. To explore this possibility, RT-PCR was used to amplify the transcripts encoding GluR2 in the neural retina. This revealed that GluR2-long transcripts, with the flop exon, are present.

Localization of ionotropic glutamate receptors to invaginating dendrites at the cone synapse in primate retina

2005 ◽  
Vol 22 (4) ◽  
pp. 469-477 ◽  
Author(s):  
DAVID J. CALKINS
Keyword(s):  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptor ◽  
Glutamate Release ◽  
Ultrastructural Localization ◽  
Bipolar Cells ◽  
Ionotropic Glutamate Receptors ◽  
Metabotropic Glutamate ◽  
Signal Light ◽  
G Protein Coupled ◽  
Microscopic Distribution

The separation of OFF pathways that signal light decrements from ON pathways that signal light increments occurs at the first retinal synapse. The dendrites of OFF bipolar cells abut the cone pedicle at basal positions distal to the site of glutamate release and express ligand-gated or ionotropic glutamate receptors (GluR). The dendrites of ON bipolar cells penetrate narrow invaginations of the cone pedicle proximal to the site of release and express the G-protein-coupled, metabotropic glutamate receptor, mGluR6. However, recent studies demonstrating the expression of GluR subunits in the rodent rod bipolar cell, known to yield an ON response to light, call this basic segregation of receptors into question. The light-microscopic distribution of many glutamate receptors in the primate retina is now well established. We reexamined their ultrastructural localization in the outer retina ofMacaca fascicularisto test systematically whether invaginating dendrites at the cone synapse, presumably from ON bipolar cells, also express one or more ionotropic subunits. Using preembedding immunocytochemistry for electron microscopy, we quantified the distribution of the AMPA-sensitive subunits GluR2/3 and GluR4 and of the kainate-sensitive subunits GluR6/7 across 207 labeled dendrites occupying specific morphological loci at the cone pedicle. We report, in agreement with published investigations, that the majority of labeled processes for GluR2/3 (70%) and GluR4 (67%) either occupy basal positions or arise from horizontal cells. For GluR6/7, we find a significantly lower fraction of labeled processes at these positions (47%). We also find a considerable number of labeled dendrites for GluR2/3 (10%), GluR4 (21%), and GluR6/7 (18%) at invaginating positions. Surprisingly, for each subunit, the remainder of labeled processes corresponds to “fingers” of presynaptic cytoplasm within the cone invagination.

Screening for MOG-IgG and 27 other anti-glial and anti-neuronal autoantibodies in ‘pattern II multiple sclerosis’ and brain biopsy findings in a MOG-IgG-positive case

2016 ◽  
Vol 22 (12) ◽  
pp. 1541-1549 ◽  
Author(s):  
Sven Jarius ◽  
Imke Metz ◽  
Fatima Barbara König ◽  
Klemens Ruprecht ◽  
Markus Reindl ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Metabotropic Glutamate Receptor ◽  
Brain Biopsy ◽  
Acid Decarboxylase ◽  
Gamma Aminobutyric Acid ◽  
Serum Samples ◽  
Metabotropic Glutamate ◽  
Histopathological Studies

Background: Histopathological studies have revealed four different immunopathological patterns of lesion pathology in early multiple sclerosis (MS). Pattern II MS is characterised by immunoglobulin and complement deposition in addition to T-cell and macrophage infiltration and is more likely to respond to plasma exchange therapy, suggesting a contribution of autoantibodies. Objective: To assess the frequency of anti-myelin oligodendrocyte glycoprotein (MOG), anti-M1-aquaporin-4 (AQP4), anti-M23-AQP4, anti-N-methyl-d-aspartate-type glutamate receptors (NMDAR) and 25 other anti-neural antibodies in pattern II MS. Methods: Thirty-nine serum samples from patients with MS who had undergone brain biopsy ( n = 24; including 13 from patients with pattern II MS) and from histopathologically non-classified MS patients ( n = 15) were tested for anti-MOG, anti-M1-AQP4, anti-M23-AQP4, anti-NMDAR, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-type glutamate receptors (AMPAR), anti-gamma-aminobutyric acid receptors (GABABR), anti-leucine-rich, glioma-activated protein 1 (LGI1), anti-contactin-associated protein 2 (CASPR2), anti-dipeptidyl-peptidase-like protein-6 (DPPX), anti-Tr/Delta/notch-like epidermal growth factor–related receptor (DNER), anti-Hu, anti-Yo, anti-Ri, anti-Ma1/Ma2, anti-CV2/collapsin response mediator protein 5 (CRMP5), anti-glutamic acid decarboxylase (GAD), anti-amphiphysin, anti-Ca/RhoGTPase-activating protein 26 (ARHGAP26), anti-Sj/inositol-1,4,5-trisphosphate receptor 1 (ITPR1), anti-Homer3, anti-carbonic anhydrase–related protein (CARPVIII), anti-protein kinase gamma (PKCgamma), anti-glutamate receptor delta 2 (GluRdelta2), anti-metabotropic glutamate receptor 1 (mGluR1) and anti-mGluR5, as well as for anti-glial nuclei antibodies (AGNA) and Purkinje cell antibody 2 (PCA2). Results: Antibodies to MOG belonging to the complement-activating immunoglobulin G1 (IgG1) subclass were detected in a patient with pattern II MS. Detailed brain biopsy findings are shown. Conclusion: This is the largest study on established anti-neural antibodies performed in MS so far. MOG-IgG may play a role in a small percentage of patients diagnosed with pattern II MS.

scholarly journals The C Terminus of the Metabotropic Glutamate Receptor Subtypes 2 and 7 Specifies the Receptor Signaling Pathways

2001 ◽  
Vol 276 (49) ◽  
pp. 45800-45805 ◽  
Author(s):  
Julie Perroy ◽  
Gustavo J. Gutierrez ◽  
Vincent Coulon ◽  
Joel Bockaert ◽  
Jean-Pilippe Pin ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Glutamate Receptor ◽  
Metabotropic Glutamate Receptor ◽  
Receptor Subtypes ◽  
Receptor Signaling ◽  
Metabotropic Glutamate ◽  
C Terminus

scholarly journals Physiological Evidence for Ionotropic and Metabotropic Glutamate Receptors in Rat Taste Cells

1999 ◽  
Vol 82 (5) ◽  
pp. 2061-2069 ◽  
Author(s):  
Weihong Lin ◽  
Sue C. Kinnamon
Keyword(s):  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate Receptor ◽  
Monosodium Glutamate ◽  
Taste Receptor ◽  
Membrane Properties ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Taste Cells

Monosodium glutamate (MSG) elicits a unique taste in humans called umami. Recent molecular studies suggest that glutamate receptors similar to those in brain are present in taste cells, but their precise role in taste transduction remains to be elucidated. We used giga-seal whole cell recording to examine the effects of MSG and glutamate receptor agonists on membrane properties of taste cells from rat fungiform papillae. MSG (1 mM) induced three subsets of responses in cells voltage-clamped at −80 mV: a decrease in holding current (subset I), an increase in holding current (subset II), and a biphasic response consisting of an increase, followed by a decrease in holding current (subset III). Most subset II glutamate responses were mimicked by the ionotropic glutamate receptor (iGluR) agonist N-methyl-d-aspartate (NMDA). The current was potentiated by glycine and was suppressed by the NMDA receptor antagonist d(−)-2-amino-5-phosphonopentanoic acid (AP5). The group III metabotropic glutamate receptor (mGluR) agonistl-2-amino-4-phosphonobutyric acid (l-AP4) usually mimicked the subset I glutamate response. This hyperpolarizing response was suppressed by the mGluR antagonist (RS)-α-cyclopropyl-4-phosphonophenylglycine (CPPG) and by 8-bromo-cAMP, suggesting a role for cAMP in the transduction pathway. In a small subset of taste cells, l-AP4 elicited an increase in holding current, resulting in taste cell depolarization under current clamp. Taken together, our results suggest that NMDA-like receptors and at least two types of group III mGluRs are present in taste receptor cells, and these may be coactivated by MSG. Further studies are required to determine which receptors are located on the apical membrane and how they contribute to the umami taste.

scholarly journals Metabotropic glutamate receptor agonists for schizophrenia

2008 ◽  
Vol 192 (2) ◽  
pp. 86-87 ◽  
Author(s):  
Paul J. Harrison
Keyword(s):  
Glutamate Receptors ◽  
Dopamine Receptor ◽  
Glutamate Receptor ◽  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate Receptor ◽  
Receptor Blocking ◽  
Receptor Agonists ◽  
Metabotropic Glutamate ◽  
Glutamate Receptor Agonists

SummaryA drug acting at metabotropic glutamate receptors has recently been reported to be an effective antipsychotic, breaking the rule that only dopamine receptor-blocking drugs have this property. The finding complements accumulating evidence that glutamatergic abnormalities are important in the pathophysiology of schizophrenia.

Structure of glutamate analogs that activate the ON bipolar cell metabotropic glutamate receptor in vertebrate retina

2003 ◽  
Vol 20 (6) ◽  
pp. 703-703
Author(s):  
NING TIAN ◽  
MALCOLM M. SLAUGHTER
Keyword(s):  
Carbon Atom ◽  
Glutamate Receptor ◽  
Bipolar Cell ◽  
Metabotropic Glutamate Receptor ◽  
Vertebrate Retina ◽  
Visual Neuroscience ◽  
Metabotropic Glutamate ◽  
Chemical Structures

There are errors in the chemical structures for Figure 1 as it was originally printed. There should be a carbon atom between the cyclopropyl ring and the phosphonate in both the trans cyclopropyl AP4 and the cis cyclopropyl AP4. Figure 1 is printed below as it should be.(article appeared in Visual Neuroscience (2003), 20, 231–240)

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