Rabbit cone bipolar cells: Correlation of their morphologies with whole-cell recordings

2001 ◽  
Vol 18 (5) ◽  
pp. 675-685 ◽  
Author(s):  
GREGORY S. McGILLEM ◽  
RAMON F. DACHEUX
Keyword(s):  
Glutamate Receptor ◽  
Bipolar Cell ◽  
Receptor Agonist ◽  
Metabotropic Glutamate Receptor ◽  
Outward Current ◽  
Membrane Resistance ◽  
Bipolar Cells ◽  
Kainate Receptor ◽  
Whole Cell ◽  
Cone Bipolar Cells

The superfused retinal slice preparation was used to examine the morphology and glutamate-activated whole-cell currents of rabbit bipolar cells. There were six morphologically distinct types of cone bipolar cells and a rod bipolar cell that had axon terminals stratifying in stratum 3 to 5 of sublamina-b. All of these bipolar cell types exhibited an outward current in response to the application of the metabotropic glutamate receptor, mGluR6, agonist AP-4 (APB), and had I/V curves indicative of membrane channel closure. Conversely, there were no currents activated during the application of kainate, the AMPA/kainate receptor agonist. These data demonstrate they were on-bipolar cells. In addition, there were six morphologically distinct cone bipolar cells that stratified in sublamina-a. Every cell with axonal arborizations in stratum 1 and 2 exhibited an inward current when the ionotropic glutamate receptor agonist kainate was applied. This current was blocked by application of the AMPA/kainate receptor antagonist CNQX. These cells also decreased their membrane resistance in response to kainate, a characteristic of the opening of channels within the plasma membrane. Without exception, no cells stratifying in sublamina-a responded to the mGluR6 agonist AP-4, further identifying them as off-bipolar cells.

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.

ON cone bipolar cells in rat express the metabotropic receptor mGluR6

1997 ◽  
Vol 14 (4) ◽  
pp. 789-794 ◽  
Author(s):  
Noga Vardi ◽  
Katsuko Morigiwa
Keyword(s):  
Bipolar Cell ◽  
Metabotropic Glutamate Receptor ◽  
Cell Types ◽  
Bipolar Cells ◽  
Ribbon Synapse ◽  
Metabotropic Receptor ◽  
Metabotropic Glutamate ◽  
Ultrathin Sections ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

AbstractThe rod bipolar cell and about five types of ON cone bipolar cells depolarize to light by employing a sign-reversing metabotropic glutamate receptor. Glutamate responses are similar in both rod bipolar and cone bipolar cells, but the receptor mediating this response (mGluRo) was so far demonstrated only in rod bipolar cells. To test if ON cone bipolar cells also express mGluR6, we immunoreacted rat retina with an antibody specific for mGluRo, and studied the staining from serial ultrathin sections. We demonstrate that mGluR6 is indeed expressed in the dendritic tips of cone bipolar cells, the majority of which receive a ribbon synapse, and thus probably are ON cone bipolar cells. We further show that half of the dendritic tips contacting the cones stain for mGluR6, thus implying that all ON cone bipolar cell types express mGluR6.

Metabotropic glutamate receptor agonist-induced hyperpolarizations in rat basolateral amygdala neurons: receptor characterization and ion channels

1996 ◽  
Vol 76 (5) ◽  
pp. 3059-3069 ◽  
Author(s):  
K. H. Holmes ◽  
N. B. Keele ◽  
V. L. Arvanov ◽  
P. Shinnick-Gallagher
Keyword(s):  
Dicarboxylic Acid ◽  
Glutamate Receptor ◽  
Basolateral Amygdala ◽  
Metabotropic Glutamate Receptor ◽  
Outward Current ◽  
Channel Blockers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Metabotropic Glutamate ◽  
Outward Currents

1. Metabotropic glutamate receptor (mGluR)-agonist-induced hyperpolarizations and corresponding outward currents were analyzed in basolateral amygdala (BLA) neurons in rat brain slice preparations with current-clamp and single-electrode voltage-clamp recording to characterize the mGluR subtype(s) and the ion channel(s) mediating this response. 2. The mGluR agonist (1S,3R)-1-amino-cyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) induced a membrane hyperpolarization or outward current in BLA neurons in a concentration-dependent manner (median effective concentration = 34 microM; range = 10-200 microM); the 1S,3R-ACPD hyperpolarizations are recorded in 89% of neurons that accommodate or cease firing in response to a 400-ms depolarizing current injection (0.5 nA). 3. mGluR agonists elicited hyperpolarizations or outward currents in a concentration-dependent manner in the following rank order of potency: (2S,3S,4S)-alpha-(carboxycyclopropyl)glycine (L-CCG-I) > 1S,3R-ACPD > (s)-4-carboxyphenylglycine = (RS)-4-carboxy-3-hydroxyphenylglycine (4C3HPG) > L-aminophosphonobutyric acid > (1S,3S)-1-amino-cyclopentane-1,3-dicarboxylic acid. In contrast, the mGluR agonists quisqualate and ibotenate induced only depolarizations in the presence of D-2-amino-5-phosphonovalerate and 6-cyano-7-nitroquinoxaline-2,3-dione in BLA neurons. 4. The 1S,3R-ACPD-induced outward current is mediated through a large-conductance calcium-dependent potassium (BK) conductance. The BK channel blockers iberiotoxin and charybdotoxin blocked the response, as did the potassium channel blockers tetraethylammonium and 4-aminopyridine; the small-conductance calcium-activated potassium channel blocker apamin did not affect the response. 5. The mGluR-agonist-induced hyperpolarization is blocked in amygdala slices from animals pretreated with pertussis toxin (PTX). 1S,3R-ACPD hyperpolarizations were recorded in neurons contralateral but not ipsilateral to the site of PTX injection. 6. The antagonist (+/-)-alpha-methyl-4-carboxyphenylglycine (MCPG, 500 microM) reduced significantly the 1S,3R-ACPD-induced hyperpolarization. 7. In conclusion, the relative potency of L-CCG-I and 4C3HPG in evoking only hyperpolarizations (outward currents) in accommodating neurons, and the observation that MCPG (500 microM) reduces the hyperpolarization, suggest that a group-II-like mGluR underlies the hyperpolarizing response. The mGluR-induced response is sensitive to iberiotoxin and to pretreatment with PTX, suggesting activation of BK channels through a group II mGluR linked to a PTX-sensitive G protein in BLA neurons.

Sign in / Sign up

Export Citation Format

Share Document